JPH0345527B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device using an optical exposure apparatus and an electron beam exposure apparatus.

Semiconductor devices are usually formed by overlapping and exposing a large number of circuit patterns, each corresponding to a large number of composite diagrams, onto an exposure material.

By the way, typical methods for exposing circuit patterns include optical exposure and electron beam exposure, which is performed by controlling the irradiation position of the electron beam, but optical exposure has a faster exposure speed because it allows batch exposure. However, it has the disadvantage that it is difficult to create fine patterns. On the other hand, although the exposure speed of electron beam exposure is inferior to that of light exposure, it has the advantage that fine patterns can be easily created. Therefore, conventionally,
When manufacturing a semiconductor device, among the many patterns that are overlapped and exposed on the exposure material to form a single semiconductor device, only the patterns with relatively many fine parts are exposed by electron beam exposure, and the other patterns are exposed by electron beam exposure. It has been proposed that the pattern is exposed onto the material by light exposure. If such a method is used, it should be possible to manufacture semiconductor devices with fine patterns in parts of circuit patterns that require overlapping exposure at high speed without compromising quality. Since there is large optical distortion in the light exposure means used when transferring a reticle (reticle, etc.) onto the exposed material using a stepper, the overlapping accuracy with the pattern exposed by electron beam exposure deteriorates, making it difficult to implement the above-mentioned technology. It was blocked.

The present invention has been made to solve the drawbacks of the prior art, and one embodiment of the present invention will be described in detail below with reference to the drawings.

Figure 1 is intended to schematically show each step of the semiconductor manufacturing method according to the present invention. As is clear from the figure, manufacturers of semiconductor devices color-code the color layers based on the specifications, as is well known. Create a composite diagram with overlays. The number of color-coded and overwritten layers is often large, and then a computer-aided design device is used to create drawing data corresponding to the pattern for each of these layers, and the data is magnetically transferred. The data is stored in the data storage means. At this time, when an enlarged original image (reticle) of the pattern is created by the pattern generator, data is added and stored in the data storage means so that a large number of marks are formed around at least one pattern. do. This mark is used to measure the distortion of the optical lens system when the reticle is transferred by the optical transfer means, as described later, and is also used to measure the distortion of the optical lens system when the reticle is transferred to the exposure material such as a wafer by the optical transfer means. It is used as a positioning mark when exposing an electron beam drawing pattern to a pattern. Furthermore, data is created so that about three marks for positioning are formed in the periphery of patterns other than one specific pattern. Next, the data from the magnetic data storage means is supplied to a pattern generator to generate a pattern that does not include a relatively fine pattern portion to be exposed by the optical exposure means among the patterns of each layer of the composite diagram. Create a reticle. Among such reticles, a reticle having the aforementioned large number of marks on the periphery of the circuit pattern is as shown in FIG. In FIG. 2, A is a region of the reticle where a pattern A, for example, is formed, and M1, M2, M3, . . . , M8 are marks. Next, this reticle having a large number of marks for strain measurement is reduced and transferred onto a wafer using an optical transfer means called a stepper. As a result, the reticle is exposed every time the stage of the stepper on which the wafer 1 is placed is moved intermittently by a certain amount, so as shown in Fig. It is transferred to the ivy position. Since there is distortion in the imaging lens system of the optical transfer means, the position of the mark transferred onto the wafer 1 is as shown in an enlarged view in FIG. Therefore,
Each mark of any one of the reticle images transferred to the wafer 1 using an electron beam exposure device is sequentially scanned with an electron beam to detect its position. As a result, the amount of distortion of the imaging lens system of the optical transfer means at the point where each mark is formed is measured by comparing the detected position of each mark with the mark position expected when there is no distortion. do. Furthermore, from the measured values of the amount of strain at each of these mark points, the amount of strain in each area (field) surrounded by dotted lines in FIG. The information is stored in the auxiliary storage means. However, the field is an area that can be drawn without moving the stage during exposure using an electron beam exposure device.

Now, images of reticles other than the first reticle are superimposed on the wafer for exposure using a stepper, and then a pattern unsuitable for optical exposure is superimposed on the wafer 1 using an electron beam exposure device. At this time, the drawing data stored in the magnetic data storage means is format-converted for use in an electron beam exposure apparatus and is supplied to the electron beam exposure apparatus.

FIG. 5 shows an example of such an electron beam exposure apparatus, in which 2 is an electron gun, 3 is a convergent lens, and 4 is an electron beam exposure device.
5 is a blanking electrode, and 5 is a deflection electrode. 6 is a stage for freely moving the mounted wafer. The electronic computer 7 stores drawing data that has been format-converted for use with the above-mentioned electron beam exposure apparatus. A blanking signal from the computer 7 is supplied to the blanking electrode 4, and a deflection signal synchronized with the blanking signal is supplied to the deflection electrode 5 via an adding circuit 8. 9 is an auxiliary storage device, and the auxiliary storage device 9 includes a fourth
The amount of distortion corresponding to each field in the figure is stored in a table.

Now, using such an apparatus, the stage 6 is moved for each field shown by dotted lines in FIG. 4 for each of the many reticle images shown in FIG. is supplied with a signal obtained by adding the irradiation position designation signal from the electronic computer 7 and the distortion value data read out from the auxiliary storage device 9 in accordance with the drawing field. When the second and subsequent reticle images are exposed overlappingly with an electron beam, the distortion of the optical transfer means is not measured by mark detection each time for the reticle image, but the previously stored optical The representative value of the distortion amount data of the target transfer means is read out and used to perform overlapping exposure. Therefore, wafer 1
Each circuit pattern drawn thereon has a distortion corresponding to the distortion of the lens system of the optical exposure means, without wasting time in measuring the amount of distortion of the optical transfer means each time. Therefore, it is possible to improve the overlapping accuracy of the optically exposed pattern and the electron beam exposed pattern on the same wafer.

In the above-described embodiments, a reticle was created using a pattern generator, and a stepper was used to transfer the reticle onto an exposure material, and a circuit pattern was overlaid on a wafer using an electron beam. Not limited to such embodiments, when exposure is performed by overlapping an exposure pattern by an optical exposure means and an exposure pattern by an electron beam,
The invention is equally applicable.

Furthermore, in the above-described embodiment, in order to distort the electron beam exposure image in accordance with the distortion of the optical lens, exposure is performed with different distortion values applied to each field. Distortion correction may be performed for each line irradiation position.

Furthermore, in the embodiments described above, distortion is applied using hardware, but the distortion may be applied by converting data for specifying the exposure position using software.

As is clear from the above description, in the present invention, a plurality of marks are formed around the circuit pattern of the original image, and a plurality of original images are transferred onto the material by the optical transfer means. The position of each of a plurality of marks in any one of the original images is detected by scanning with an electron beam, and the distortion of the optical transfer means is determined based on the position information of each detected mark. The amount of distortion in each field of the transferred circuit pattern is determined based on the amount of distortion, the amount of distortion is stored in a storage means in correspondence with each field, and the amount of distortion is stored in a storage means in correspondence with each field, and when each field in each original image is exposed overlappingly with an electron beam, the amount of distortion is determined. Since the amount of distortion in the field is read from the storage means and the projection position of the electron beam is shifted in accordance with the amount of distortion of the optical transfer means in the field based on the reading, a single original image is exposed only once. determine and store the amount of distortion of the optical transfer means in each field;
When overlapping exposure with an electron beam on another original image,
The distortion amount of the field corresponding to each field of the original image is read out, and the projection position of the electron beam is shifted to perform overlapping exposure, and the distortion of the optical transfer means using mark detection when overlapping exposure is performed on other original images. Since the measurement of the amount can be omitted, highly accurate overlapping exposure can be performed with high throughput.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing one embodiment of the present invention, FIG. 2 is a diagram showing an example of marks formed around a pattern forming area of a reticle, and FIG. 3 is a flowchart showing an embodiment of the present invention. A diagram showing a reticle image transferred onto a wafer; FIG. 4 is a diagram explaining distortion measurement by detecting marks;
FIG. 5 is a diagram showing an example of an apparatus for carrying out the present invention. M1, M2,..., M8: mark, 1: wafer, 2: electron beam, 5: deflection electrode, 7: electronic computer, 8: addition circuit, 9: auxiliary storage device.

Claims (1)

[Claims] 1 An enlarged or reduced original image is created based on the drawing figure information, and the created original image is transferred onto the material to be exposed every time the material to be exposed moves by a predetermined amount using an optical transfer means, and different images on the material are transferred. When multiple exposures of the same original image are made at the same position and an area on the material that can be drawn with an electron beam without moving the material is called a field, each of the original images is divided into a plurality of fields, and each field is exposed to the electron beam. A method in which a circuit pattern is overlapped and exposed with an electron beam on each of the original images exposed on the material by moving the material each time the material is exposed to light, based on the drawn figure information, the circuit pattern is exposed around the circuit pattern of the original image. A plurality of marks are formed on the material, and the position of each of the plurality of marks in any one of the plurality of original images transferred onto the material by the optical transfer means is determined using an electron beam. Detecting the detected marks by scanning, and determining the amount of distortion in each field of the transferred circuit pattern based on the distortion of the optical transfer means based on the position information of each detected mark, and calculating the amount of distortion. The optical transfer means is stored in a storage means in correspondence with each field, and when each field in each original image is exposed overlappingly with an electron beam, the amount of distortion in that field is read from the storage means, and based on the distortion amount in the field, the optical transfer means in the field is 1. A method of manufacturing a semiconductor device, characterized in that exposure is performed by shifting the projection position of an electron beam according to the amount of distortion.