JPH07211618A - Design pattern exposure method - Google Patents

Abstract

(57) [Summary] [Purpose] To correct lens distortion for nonlinear components of design patterns. [Configuration] A reticle 3 having a design pattern is aligned with an existing pattern on a semiconductor substrate,
In a method of exposing a design pattern by imaging a design pattern on a semiconductor substrate using a lens 11, the reticle 3 is divided so that a nonlinear component of the design pattern formed on the reticle can be approximated to a linear component. , The divided reticles 3 are independently exposed to form one design pattern on a semiconductor substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method for exposing a design pattern on a semiconductor substrate, and more particularly to a technique effective when applied to a reduction or equal-magnification projection exposure method.

[0002]

2. Description of the Related Art In a conventional reduction projection exposure method, a single reticle on which a design pattern of the same size or 5 to 10 times the original size is formed is aligned with an existing pattern on a semiconductor substrate and reduced. The design pattern is formed on the semiconductor substrate by forming an image of the design pattern on the semiconductor substrate by using a lens or an equal-magnification lens and exposing the image.

[0003]

DISCLOSURE OF THE INVENTION The present inventors have found the following problems as a result of examining the above prior art.

In the conventional reduction projection exposure method, when a design pattern is projected onto a semiconductor substrate through a reduction lens or a unity magnification lens, distortion (lens distortion) occurs in the design pattern.

Since this lens distortion varies depending on the lens used, the correction amount of this distortion is calculated during alignment, or the correction amount is calculated in advance by experiment or inspection data and is managed as an apparatus parameter for correction. However, this correction has a problem that it is effective only for the linear component (straight line portion) of the design pattern and cannot be applied to the nonlinear component.

An object of the present invention is to provide a technique capable of correcting lens distortion for a non-linear component of a design pattern.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0008]

Of the inventions disclosed in the present application, a representative one will be briefly described below.
It is as follows.

The reticle on which the design pattern is formed is aligned with the existing pattern on the semiconductor substrate,
In a method of exposing a design pattern by imaging a design pattern on a semiconductor substrate using a lens, a reticle is divided so that a nonlinear component of a design pattern formed on the reticle can be approximated to a linear component, and The divided reticles are independently exposed to form one design pattern on the semiconductor substrate.

[0010]

According to the above-described means, the reticle on which the design pattern is formed is aligned with the existing pattern on the semiconductor substrate, and the design pattern is imaged on the semiconductor substrate by using the lens to expose the design pattern. In the exposure method, the reticle is divided so that the non-linear component of the design pattern formed on the reticle can be approximated to a linear component, and the divided reticles are exposed independently to form one design pattern on the semiconductor substrate. Since the non-linear component of the design pattern can be replaced by the linear component and the correction of the linear component of the conventional design pattern can be applied to the non-linear component, the lens distortion can be applied to the non-linear component of the design pattern. Can be corrected.

The structure of the present invention will be described below together with embodiments.

In all the drawings for explaining the embodiments, those having the same function are designated by the same reference numerals and their repeated description will be omitted.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view for explaining a procedure for dividing and forming a reticle on which a design pattern is formed, which is an embodiment of the present invention.

In FIG. 1, 1 is a design pattern, 2 is a pattern approximated to a linear component, 3 is a reticle, and 4 is a mask alignment target.

The procedure for dividing and forming the reticle on which the design pattern is formed in this embodiment will be described by taking the design pattern 1 shown in FIG. 1A as an example.

First, a design pattern 1 formed on a reticle including a linear component and a non-linear component as shown in FIG.
To approximate. The approximation at this time can be made in any number of ways, and the finer the approximation, the more accurate the design pattern can be obtained, and the more accurate the lens distortion at the time of exposure, but in the present embodiment, The case where the design pattern 1 is approximated like the approximation pattern 2 of FIG. 1B is taken as an example.

After the approximate pattern 2 is determined as shown in FIG. 1 (b), the reticle is divided into four parts so that the approximate pattern 2 is obtained as shown in FIG. 1 (c).

Finally, the four-divided reticles 3A to 3D
Forming a mask alignment target corresponding to each of.

Next, a procedure for exposing the design pattern using the reticles 3A to 3D described above will be described.

FIG. 2 shows a schematic structure of the exposure apparatus of this embodiment, and FIG. 2 (a) is a side view thereof.
FIG. 2B shows a view seen from above.

In FIG. 2, 10A to 10D are alignment systems, 11 is a projection optical system including a lens, and 12 is a stage for exposing a semiconductor substrate. Alignment systems 10A to 10D are a reticle alignment section and a semiconductor substrate which will be described later. It consists of an alignment unit.

FIG. 3 is for explaining an exposure procedure using the above-described exposure apparatus shown in FIG.

In FIG. 3, 20 is a reticle alignment section, 21 is a semiconductor substrate alignment section, and 22 is a reticle transfer robot.

The reticle alignment unit 20 in FIG. 3A is a TTR system which is composed of a microscope, a light receiving element and the like, and corrects the position of the reticle through the reticle. The semiconductor substrate alignment unit 21 includes a laser light source and a beam splitter. , A TTL system for position confirmation and correction through a projection optical system 3 (lens) including a light receiving element and the like.

These alignment systems are provided as many as the number of divided reticles, and in the case of four divisions, they are provided at four locations so as to correspond to each reticle. Note that FIGS. 3A and 3B show the reticle alignment unit 20, the semiconductor substrate alignment unit 21, and the reticle transfer robot 22 at only one of the four positions.

Further, in the present invention, the semiconductor substrate alignment section 21 is not limited to the TTL system.

The procedure of the exposure method using the exposure apparatus of this embodiment is as follows. First, as shown in FIG. 1, the reticles 3A to 3D are first prepared, and the reticles 3A to 3 thus prepared are prepared.
D is set by the reticle transport robot 22.

Then, as shown in FIG. 3B, the semiconductor substrate alignment section 21 confirms the position of the semiconductor substrate (not shown) to be exposed, and the reticle alignment section 20 detects the mask alignment target 4 of the corresponding reticle. Check the position and make corrections.

The position correction (offset, rotation, etc.) of each reticle at this time is performed by measuring the distortion information of the lens, the semiconductor substrate alignment information, the exposure accuracy history information that has been exposed so far, and each overlay component. Based on the setting values (device parameters), reticle manufacturing error information, lens control information controlled by atmospheric pressure, etc., the information for best superposition of the reticle and the semiconductor substrate is transferred to a reticle controller (not shown). To do.

When the position correction of the reticle is completed, the design pattern is exposed on the semiconductor substrate with g-line (i-line, excimer, or X-ray is acceptable).

Finally, the process ends when all the divided reticles are exposed.

Therefore, in the design pattern exposure method, the reticle on which the design pattern is formed is aligned with the existing pattern on the semiconductor substrate, and the lens is imaged on the semiconductor substrate using the lens to expose the reticle. The reticle is divided so that the nonlinear component of the design pattern formed on the reticle can be approximated to the linear component,
By exposing each of the divided reticles independently to form one design pattern on the semiconductor substrate, the non-linear component of the design pattern can be replaced by the linear component, and the linear component of the conventional design pattern can be corrected. Since it can be applied to a non-linear component, it becomes possible to correct the lens distortion for the non-linear component of the design pattern.

The inventions made by the present inventors are as follows.
Although the present invention has been specifically described based on the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the scope of the invention.

[0034]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

The reticle on which the design pattern is formed is aligned with the existing pattern on the semiconductor substrate,
In a method of exposing a design pattern by imaging a design pattern on a semiconductor substrate using a lens, a reticle is divided so that a nonlinear component of a design pattern formed on the reticle can be approximated to a linear component, and By exposing each divided reticle independently and forming one design pattern on the semiconductor substrate, the non-linear component of the design pattern can be replaced by the linear component, and the correction of the linear component of the conventional design pattern can be performed by the non-linear component. Since it can also be applied to the component, it becomes possible to correct the lens distortion for the nonlinear component of the design pattern.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a procedure of dividing and forming a reticle on which a design pattern is formed, which is an embodiment of the present invention.

2A and 2B show a schematic configuration of an exposure apparatus of this embodiment, FIG. 2A is a side view thereof, and FIG. 2B is a top view thereof.

FIG. 3 is a diagram for explaining an exposure procedure using the exposure apparatus shown in FIG.

[Explanation of symbols]

1 ... design pattern, 2 ... pattern approximated to linear component,
3 ... Reticle, 4 ... Mask alignment target, 1
0A to 10D ... Alignment system, 11 ... Projection optical system including lens, 12 ... Stage for exposing semiconductor substrate,
20 ... Reticle alignment part, 21 ... Semiconductor substrate alignment part, 22 ... Reticle transfer robot.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiichiro Shirai 2326 Imai, Ome-shi, Tokyo Hitachi, Ltd. Device Development Center

Claims (1)

[Claims] 1. A method for exposing a design pattern, wherein a reticle having a design pattern formed thereon is aligned with an existing pattern on a semiconductor substrate, and the lens is imaged on the semiconductor substrate by using a lens to expose the reticle. The reticle is divided so that the nonlinear component of the design pattern formed on the reticle can be approximated to a linear component, and each divided reticle is exposed independently to form one design pattern on the semiconductor substrate. A method for exposing a characteristic design pattern.