JPH04297016A - Preparing method of x-ray mask - Google Patents

Abstract

PURPOSE:To provide the X-ray mask having in-plane positional accuracy of a mask pattern. CONSTITUTION:Marker patterns 4 formed at every field x1-x4 are detected prior to the drawing of an X-ray mask, and drawing is conducted at every field x1-x4 while successively correcting positions. Continuity among the fields x1-x4 of mask patterns 3a crossing the fields x1-x4 is improved, the X-ray mask, in which these mask patterns 3a are formed accurately at positions according to a design, and the transfer accuracy of said X-ray mask is enhanced remarkably when said X-ray mask is used for X-ray lithography.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray mask manufacturing method that improves positioning accuracy during mask pattern drawing.

0002

[Prior Art] In X-ray lithography, a mask pattern is exposed and transferred onto a wafer at the same magnification, so the mask accuracy directly affects the transfer accuracy, and various research is being actively conducted on membrane materials. There is.

On the other hand, a generally known method for making a same-size X-ray mask is to stack a membrane and an absorber over the entire surface of a substrate, and then use ion beam exposure or electron beam exposure and etching. A desired pattern (that is, a mask pattern) is formed on the absorber using a technique, and back etching is performed to hollow out the substrate in the X-ray exposure area before or after forming the pattern.

However, during the above-mentioned ion beam exposure or electron beam exposure, the deflection distortion of the beam due to electrostatic and electromagnetic deflection increases toward the edges of the drawing area, so it is not possible to write the entire area with only the deflection means. becomes difficult to do.

Therefore, in addition to such electrostatic and electromagnetic deflection, as shown in FIG.
A field exposure method is also used in which the stage 6 on which the images are placed is moved step by step to expose each field x1 . . . xn, thereby drawing the entire area.

To describe this drawing method in more detail, first, the electron beam emitted from the electron gun 7 is focused through an electrostatic lens 8, and the direction of the beam is directed to a desired direction by an electrostatic/electromagnetic deflection system 9. It is controlled and irradiated onto the mask X. However, since the possible angle of deflection is limited due to the occurrence of deflection distortion, etc., in actual exposure of the entire surface of the chip, the stage 6 on which the mask So stage 6 X, Y
The exposure is performed in combination with a method in which exposure is performed by dividing into small fields x1 . . . xn. That is, the deflection system 9 exposes the field that can be exposed, and then the stage 6
is stepped to move to the next field, where the electron beam is swung again by the deflection system 9 to perform drawing. Repeat the above operations to complete mask drawing.

[0007]

[Problems to be Solved by the Invention] However, since ion beam exposure and electron beam exposure are performed in a vacuum, it is very difficult to fix the mask X on the stage 6 by adsorption so that it does not move. Moreover, even if the mask X is mechanically fixed on the stage 6 without suction, the mask X on the stage 6 will shift within a delicate range as step feeding is repeated. Therefore, the position of the stage 6 is adjusted by the length measuring system 11a.
, 11b, there is a problem in that the positional accuracy during mask drawing is very poor, as shown in FIG. 4, no matter how accurately monitoring and drawing are performed.

The present invention was devised in view of the above-mentioned problems in the prior art, and aims to improve the method of creating an X-ray mask and increase the positional accuracy of the mask pattern. It is also naturally intended that this improved accuracy will further improve the positional accuracy within the chip surface, that is, the alignment accuracy when exposure is performed using the X-ray mask.

[0009]

[Means for Solving the Problems] The configuration of the present invention is based on the following two methods of making an X-ray mask, and is implemented in both methods, and therefore will be explained separately as two inventions. become. The first is the configuration shown in the above-mentioned prior art, which has a membrane that constitutes a mask and an absorber, and after laminating the absorber on the membrane, ion beam exposure is performed to directly or By performing etching together with electron beam exposure, the absorber is processed into a desired mask pattern. ■ The other method is to first form a resist pattern by performing ion beam exposure or electron beam exposure on the membrane, and then layer an absorber on the exposed membrane between the resist patterns to obtain the desired mask pattern. be.

[0010] The first invention of the present application assumes the configuration (2) as a prerequisite, and forms a marker pattern as a position reference on the absorber before exposure, and sequentially performs position correction while monitoring this marker pattern. This involves repeated field exposure.

[0011] In the second invention, using the above configuration (2) as a prerequisite configuration, a marker pattern serving as a position reference is formed on the membrane before exposure, and the position is sequentially corrected while monitoring this marker pattern to form the above-mentioned field. This involves repeated exposure.

In both configurations, during field exposure, drawing is not performed while monitoring the stage position, but drawing is performed while monitoring the X-ray mask, especially the position within the field where drawing is to be performed.
The in-plane positional accuracy of the pattern is significantly improved compared to the conventional case. Therefore, it is most desirable to form the marker pattern in each field, and in that case, it is preferable that at least one marker pattern is provided in each field. Of course, it is also possible to provide them intermittently based on certain rules.

[0013] The method for forming these marker patterns is to use photolithography, and when semiconductor devices are manufactured using several types of X-ray masks, the same reticle is used for a series of masks. When the above-mentioned marker pattern is created using the mask, the position of the marker does not vary between masks and is always formed at a constant location.

Furthermore, these marker patterns can be formed by cutting off a part of the surface of the absorber layer or membrane, or by laminating them on the surface of the absorber or membrane. , when forming on an absorber as in the first invention configuration (particularly when the surface is scraped off), so as to sufficiently ensure the X-ray shielding property of the absorber (thickness that can sufficiently secure the light shielding property) must be left in place).

[0015]

[Examples] Specific examples of the first invention method of the present application will be described in detail below.

FIG. 1 is a process diagram showing an embodiment of the X-ray mask manufacturing method of the first invention.

First, as shown in FIG. 1(a), a membrane 2 and an absorber 3 are laminated on a substrate 1.

Next, as shown in FIG. 3B, a cross-shaped marker pattern 4 was created on the absorber 3 for each field. At this time, an optical stepper was used to create a series of masks using the same reticle, and the etching depth was set to such a level that the absorber 3 could sufficiently block X-rays.

Marker pattern 4 created in this way
As shown in FIG. 2(a), each of the fields x1, x2, x3, and x4 constituting one chip is located at a fixed location in the upper right corner.

After that, a resist is further applied, and ion beam exposure (or electron beam exposure and etching) is performed while monitoring the marker pattern 4 for each field to grasp the mask position, as shown in FIG. 1(c). A resist pattern 5 for forming a mask pattern was formed.

After that, the absorber 3 is etched and the resist pattern 5 is removed to form a desired mask pattern 3a as shown in FIG. (depicted in large size).

Finally, as shown in FIG. 1(e), the substrate 1
An X-ray mask was created by back-etching the X-ray exposed area.

As shown in FIG. 2(b), the planar state of the X-ray mask thus obtained is such that the mask pattern 3a formed across the fields is shifted between the fields. There was almost no positional distortion.

As described above, in this embodiment, since the pattern is drawn while monitoring the position of the marker pattern 4 for each field, no positional deviation occurs during field step feeding. Furthermore, if the marker patterns 4 of a series of X-ray masks are made using the same reticle, the reticle will not be distorted, so even if the stepper lens is distorted, the marker patterns 4 of the same shape will always be at a constant position. Therefore, no relative positional deviation between the masks occurred. Furthermore, when the marker pattern 4 is formed by scraping off a part of the surface of the absorber 3, if the depth is made shallow as in this embodiment, even if the marker pattern 4 is formed on the mask pattern 3a, , sufficient light-shielding properties are ensured.

On the other hand, although it was not carried out in this embodiment, EGA (Enhancer) used in optical lithography technology was used.
If an alignment technique based on statistical processing of the chip position called ced Global Alignment is applied to the detection of the marker pattern 4 (that is, a plurality of marker patterns 4 are measured and subjected to statistical processing to calculate the position of each field, In the unlikely event that even one marker pattern 4 cannot be detected or is inaccurately detected due to pattern roughness, etc., the position of that field can be determined from the position of the surrounding fields based on the above statistical processing data. ), marker pattern 4
It is also possible to improve the detection accuracy.

[0026]

According to the configuration of the present invention described in detail above, during field exposure, the marker pattern provided in each field is detected, and the exposure of each of these fields is performed while sequentially correcting the position each time. Therefore, it is possible to obtain an X-ray mask with high in-plane positional accuracy, that is, with high continuity of mask patterns spanning between fields, and with these mask patterns formed accurately at the designed positions. becomes possible. As a result, when this X-ray mask is used for X-ray lithography, the transfer accuracy will be significantly improved.

[Brief explanation of drawings]

FIG. 1 is a process explanatory diagram of an X-ray mask manufacturing method according to an embodiment of the present invention.

FIG. 2 is a plan view of an X-ray mask showing a state where a marker pattern is formed for each field and a state of a mask pattern obtained as a result of implementing the method of the present invention using the marker pattern.

FIG. 3 is an explanatory diagram of a field exposure method performed when creating an X-ray mask.

FIG. 4 is a mask plan view showing a positional shift state of a mask pattern in an X-ray mask made by a conventional X-ray mask making method.

[Explanation of symbols]

1 Board 2 Membrane 3 Absorber 3a Mask pattern 4 Marker pattern 5 Resist pattern

Claims (8)

[Claims] 1. A mask comprising a membrane and an absorber, and after the absorber is laminated on the membrane, ion beam exposure or electron beam exposure is performed to remove the absorber directly or with etching. In an X-ray mask making method in which an X-ray mask is made by processing a body into a desired pattern, a marker pattern is formed on the absorber as a position reference before the exposure, and this marker pattern is monitored to sequentially correct the position. 1. A method for making an X-ray mask, characterized in that ion beam exposure or electron beam exposure is performed during the process. 2. The method for producing an X-ray mask according to claim 1, wherein the marker pattern is formed using photolithography, and a series of masks is provided when a semiconductor device is produced using several types of X-ray masks. 2. The X-ray mask manufacturing method according to claim 1, wherein the marker pattern is created using the same reticle for each series. 3. In the method for producing an X-ray mask according to claim 1, when the stage on which the mask is placed is moved for each field and drawing is performed by ion beam exposure or electron beam exposure, 3. The method of creating an X-ray mask according to claim 1, wherein each field includes at least one marker pattern. 4. The method for making an X-ray mask according to claim 1, wherein the marker pattern is formed by scraping a part of the surface of the absorber layer or by laminating it on the surface of the absorber layer. An X-ray mask manufacturing method according to any one of claims 1 to 3, characterized in that: 5. Performing ion beam exposure or electron beam exposure on the membrane to form a resist pattern,
In an X-ray mask manufacturing method in which a mask pattern is created by laminating an absorber on the exposed membrane between the resist patterns, a marker pattern serving as a position reference is formed on the membrane before the exposure, and this marker pattern is monitored. A method for making an X-ray mask, characterized in that ion beam exposure or electron beam exposure is performed while sequentially correcting the position. 6. The X-ray mask manufacturing method according to claim 5, wherein the marker pattern is formed using photolithography, and a series of steps are performed when manufacturing a semiconductor device using several types of X-ray masks. For the mask series,
6. The method for creating an X-ray mask according to claim 5, wherein the marker patterns are created using the same reticle. 7. In the method for producing an X-ray mask according to claims 5 to 6, when drawing is performed by ion beam exposure or electron beam exposure by moving the stage on which the mask is placed for each field, 7. The method for producing an X-ray mask according to claim 5, wherein each field includes at least one marker pattern. 8. The method for making an X-ray mask according to claim 5, wherein the marker pattern is formed by scraping a part of the surface of the membrane or by laminating the surface of the membrane. An X-ray mask manufacturing method according to any one of claims 5 to 7.