JP2000206672A - Dual photomask equipped with binary pattern and phase shift pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dual photomask used in photolithography in the case of producing an integrated circuit and capable of performing double exposure operation on a semiconductor wafer without mask tooling. SOLUTION: This dual photomask 10 is equipped with a reticle glass plate 12 where a phase shift mask(PSM) chrome area 14 and a binary (BIN) chrome area 16 are adjacently arranged. When the photomask 10 is used, it is shifted between two previously decided positions that a pattern from the area 16 can be transferred to a wafer at the first position and the pattern from the area 14 can be transferred at other position. An exposure scanner is used to expose the wafer through the photomask 10. By this photomask 10, a defect such as the positional deviation of pattern transfer occurring because two masks are used in the case of the conventional technique is eliminated, further yield is improved and the production cost of the wafer is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor manufacturing technique. In particular, the present invention relates to a dual photomask having a binary (BIN) pattern and a phase shift mask (PSM) pattern used in a photolithography double exposure operation.

[0002]

BACKGROUND OF THE INVENTION The achievement of integrated circuit manufacturing requires very precise techniques. Even the smallest errors in the manufacturing process can reduce the reliability of the manufactured wafers or render them unusable and unusable, degrading wafer yield.

[0003] Photolithography is the most important step in semiconductor manufacturing. Photolithography is used to form a predetermined pattern in a photoresist layer for the manufacture of various circuit elements, for example, MOS (metal-oxide semiconductor) elements and impurity doped regions in integrated circuits. Several photolithography steps are typically required to complete the IC manufacturing process. The photolithography process includes three basic steps: coating, exposing, and developing.

In a coating step, a layer of photoresist is applied to cover the entire top surface of the wafer. In an exposure step, the photoresist layer is exposed to light through a predetermined photomask. Then, in a development step, the photoresist layer is developed to remove either the exposed or unexposed portions to form a latent pattern transferred into the photoresist layer. In this photolithography process, the pattern transfer from the photomask to the photoresist layer requires precise alignment from the photomask to the photoresist layer. Otherwise, the entire manufactured wafer may be unusable and must be discarded.

A common method of producing a transferred pattern with high resolution is to use a stepper-controlled binary mask (BIN) and a phase shift mask (PSM) to form a photomask in a double exposure operation. Processing the resist layer. In this double exposure operation, the photoresist layer is first exposed as a first exposure to a BIN mask, and then for a second exposure, the BIN mask is replaced with a PSM mask (referred to as mask retooling).

However, one disadvantage of the above-described double exposure operation is that the pattern transfer with the second mask is performed so as to accurately align with the previously exposed area in the photoresist layer using the first mask. It is difficult to accurately position the second mask in such a manner as to allow the following. If misaligned, the manufactured wafer may be defective, thus reducing the wafer manufacturing yield.

[0007]

Accordingly, it is an object of the present invention to provide a BIN pattern and PSM which can be used to perform a double exposure operation without mask retooling.
It is to provide a dual photomask with a pattern.

It is another object of the present invention to provide a dual photomask having a BIN pattern and a PSM pattern, which can eliminate the displacement of a transferred pattern caused by using two masks.

It is yet another object of the present invention to provide a dual photomask with a BIN pattern and a PSM pattern that allows for high yield wafer fabrication.

According to the foregoing and other objects of the present invention,
A dual photomask with a BIN pattern and a PSM pattern is provided.

[0011]

SUMMARY OF THE INVENTION A dual photomask of the present invention comprises a reticle glass plate, a PSM chrome region formed on the reticle glass plate, and a PSM chrome region formed on the reticle glass plate and adjacent to the PSM chrome region. And a BIN chrome region arranged in a vertical direction. During operation, the dual photomask, in the first position, allows the pattern from the BIN chrome area to be transferred to the wafer,
At other positions, the pattern from the PSM chrome area is shifted between two predetermined positions, which allows the pattern to be transferred.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS The invention can be more fully understood by reading the detailed description of an embodiment.

An embodiment of a dual photomask according to the present invention is shown below with reference to FIGS.

Referring to FIGS. 1 and 2, the dual photomask of the present invention, collectively designated herein by the reference numeral 10, is constructed on a reticle glass plate 12, typically 5 inches in size. Is done. PSM chrome area 14
The BIN pattern realized by the BIN chrome region 16 and the PSM pattern realized by the above are formed on the reticle glass plate 12 in an adjacent manner. PS
The M chrome region 14 and the BIN chrome region 16 are used for pattern transfer during a photolithography process. Each PSM chrome area 14 and BIN chrome area 1
The function of No. 6 is the same as the normal PSM mask and BIN mask, and the description thereof will not be described in further detail. The PSM chrome regions 14 can cause a phase shift from 0 ° to 180 ° in the transferred pattern.

In addition, the aiming point 17 is used for positioning the dual photomask 10 in the photolithography step so that the PSM chrome region 14 and the BIN chrome region 1 are located.
6 are arranged. Further, the thin film frame 18
Are the PSM chrome region 14 and the BIN chrome region 16
For protection from being contaminated or damaged by dust and foreign matter.
Used to cover both 4 and BIN chrome regions 16.

FIGS. 3 and 4, respectively, are schematic diagrams used to depict the application of a dual photomask during a photolithographic step of performing a double exposure operation on wafer 20. FIG. Here, it is assumed that the pattern defined by the PSM chrome area 14 and the pattern defined by the BIN chrome area 16 are transferred to the target area designated by reference numeral 23.

In the double exposure operation, the first step is to place the dual photomask 10 at a first predetermined position indicated by reference numeral 21. At this position 21, the BIN chrome region 16 on the dual photomask 10 is aligned with the target region 23. The exposure scanner 24 is
Then the target area 23 through the BIN chrome area 16
Used to expose the light.

Subsequently, the dual photomask 10 is shifted to the right by a predetermined movement to a second predetermined position indicated by reference numeral 22. At this position, the PSM chrome region 14 on the dual photomask 10 is aligned with the target region 23. Next, the same exposure scanner 24
Used to expose the target area 23 with light through the M chrome area 14.

As a result of the double exposure operation described above,
The target area 23 receives successively the pattern from the BIN chrome area 16 and then the pattern from the PSM chrome area 14. Thereby, the double exposure operation on the target region 23 by the dual photomask 10 of the present invention is completed. The above-described double exposure operation is repeated until all target regions in the wafer are exposed.

As will be understood from the above description, the dual photomask of the present invention enables a double exposure operation to be performed without mask retooling as in the prior art. This makes it possible to more accurately align the second transferred PSM pattern with the first transferred BIN pattern. Therefore,
The present invention can improve the yield of wafer manufacturing.
Further, the integration of PSM chromium and BIN chromium regions on the same plate can significantly reduce the cost of manufacturing dual photomasks.

In conclusion, the present invention provides a P
It is characterized by the integration of SM chrome and BIN chrome regions (referred to as a dual photomask that allows for more accurate double exposure operations without misalignment).
The present invention can therefore improve yield and reduce the cost of wafer fabrication.

The present invention has been described using the embodiments. However, the scope of the present invention is not limited only to the contents described in the embodiments. On the contrary, various improvements and similar arrangements are included in the scope of the invention. The claims should, therefore, be interpreted in the broadest sense and include all such modifications and similar arrangements.

[0023]

By using the dual photomask of the present invention, a double exposure operation can be performed without mask retooling, so that the double exposure operation can be performed accurately without displacement. Therefore, the yield can be improved, and the cost of manufacturing the wafer can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a dual photomask of the present invention.

FIG. 2 is a schematic view of a cross section of a dual photomask of the present invention.

FIG. 3 is a schematic diagram illustrating the application of a dual photomask for performing a double exposure operation on a wafer.

FIG. 4 is a schematic diagram showing the application of a dual photomask for performing a double exposure operation on a wafer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Dual photomask 12 ... Reticle glass plate 14 ... PSM chrome area 16 ... BIN chrome area 17 ... Aiming point 18 ... Thin film frame 20 ... Wafer 21 ... First predetermined position 22 ... Second predetermined Position 23: Target area 24: Exposure scanner

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H095 BA02 BB02 BB03 BC19 BE03 BE08 5F046 AA12 AA25 BA04 BA08 CB17 EB02

Claims (6)

[Claims] 1. A reticle glass plate, a PSM chrome region formed on the reticle glass plate, and a BIN chrome region formed on the reticle glass plate and arranged adjacent to the PSM chrome region. A dual photomask, comprising: 2. A sighting point disposed around the PSM chromium region and the BIN chromium region on the reticle glass plate to assist positioning of the dual photomask in a photolithography process. The dual photomask according to claim 1, wherein: 3. The dual according to claim 1, further comprising a thin film frame covering the PSM chrome region and the BIN chrome region to protect the PSM chrome region and the BIN chrome region. Photo mask. 4. The size of the reticle glass plate is 5
The dual photomask of claim 1, wherein the photomask is inches. 5. The method of claim 1, wherein the PSM chromium region is between 0 ° and 18
The dual photomask according to claim 1, wherein a phase shift of up to 0 ° can be caused. 6. The dual photomask according to claim 1, wherein the dual photomask is used in a photolithography process in which an exposure scanner is used to expose a wafer through the dual photomask.