JPS63205917A - Mask method - Google Patents

Abstract

PURPOSE:To obtain very fine pattern in the vicinity of a photolithographic limit, by combining a part near a photolithographic limit of a first mask pattern with a part near a photolithographic limit of a second mask pattern. CONSTITUTION:A first mask pattern M1, which has selectivity to a material to be processed, is formed. A second mask pattern M2, which is different from the pattern M1 and has selectivity to the material to be processed, is formed on the pattern M1. A pattern M3 is formed from a combination of patterns M1 and M2, and required processing is performed for the material to be processed. Only a superposed portion S0 composed of opening patterns in the patterns M1 and M2 is an opening pattern in the pattern M3. The pattern M3 is formed to become an approximately photolithographic limit by combining sizes of its edge parts. Thus, a fine pattern can be obtained in the vicinity of the photolithographic limit.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of Application The present invention is directed to selectively processing objects to be processed when performing necessary processing such as etching processing and ion implantation processing in the manufacturing process of semiconductor devices. Regarding mask method.

B0 Summary of the Invention The present invention provides a mask method for selectively processing an object when performing required processing such as etching processing or ion implantation processing, which comprises a combination of first and second mask patterns. By selectively processing the object with a pattern, finer processing can be achieved.

C0 Conventional Technology In the manufacturing technology of semiconductor devices such as LSI and VLSI, a vacuumed mask is usually used because predetermined areas are selectively processed during etching or ion implantation. There is.

For example, in an etching process, a resist layer is first formed on the surface of the object to be etched, and this resist layer is exposed to pattern light through a photomask and then developed to form a predetermined pattern on the resist layer. to form. Using the resist layer formed in this predetermined pattern as a mask, etching is performed to obtain an object to be etched having a shape according to the pattern.

D0 Problems to be Solved by the Invention In the conventional mask method, when performing fine processing, it is necessary to make the pattern itself fine and to form a photoresist or the like in a fine shape by exposure.

However, such photolithography technology has its limits, and it is not easy to obtain fine patterns that are close to the limits of photolithography.For example, in order to follow the miniaturization of semiconductor devices, When opening contact holes using size pattern rules, even if a mask with a fine rectangular pattern is initially formed, the pattern ends up with rounded corners. will occur.

Such a change in the shape of the contact hole causes a difference between the designed resistance value and the resistance value of the actual device, which causes a problem in the operation of the device.

Further, in the selective epitaxial growth technique, the exposed portion of the single crystal is formed by a mask, and in the ion implantation technique, a mask is also used to selectively dope, but similar problems arise.

Therefore, in view of the above-mentioned problems, the present invention aims to provide a mask method for realizing fine processing near the limit value of photolithography.

Means for Solving Problem E1 FIGS. 1A to 1C are diagrams for explaining the basic steps of the present invention in the order of the steps.

First, a first mask pattern M1 that is selective to the object to be processed as shown in FIG. 1a is formed.

Here, as an example, it is a rectangular open pattern with a length Xi in the X direction and a length Yl in the Y direction.

Next, a second mask pattern M2 is formed on the first mask pattern, which is a pattern different from the first mask pattern as shown in FIG. do. This second mask pattern M2 is, for example, a rectangular open pattern with a length of X2 degrees in the X direction and a length of Yl1 in the Y direction.

Then, a pattern M3 consisting of a combination of the first and second mask patterns as shown in FIG. Only the overlapping portion So of the open pattern of the second mask pattern M2 becomes the open pattern, and the area W and the area 31. Both S2 function as a mask area for the object to be processed. It goes without saying that the first and second mask patterns ML and M2 are not limited to the rectangular open pattern described above.

F0 effect With a single mask pattern, it is difficult to open windows such as minute contact holes due to the limitations of photolithography, but with the mask method of the present invention, as is clear from FIGS. Length X of first mask pattern M1
Even if the length Y2 of the second mask pattern M2 and the length Y2 of the second mask pattern M2 are respectively set to dimensions close to the limits of photolithography, the lengths X2. Y
l can be configured with a margin from the above limit value.

Therefore, the adverse effects such as fluctuations in exposure amount and single diffraction of light are alleviated by the first and second mask patterns Ml and M2, respectively, and the pattern M3, which is a combination of the first and second mask patterns, is Depending on the combination, the size of the edge portion approaches the limit of photolithography and can easily become minute. Therefore, by performing necessary processing using such a mask method, fine processing close to the limit of photolithography can be achieved.

G. Example Preferred embodiments of the present invention will be described with reference to the drawings.

First Example The mask method of this example is a method for obtaining a mask for forming a contact hole of a certain device by etching, and it is possible to easily obtain a contact hole with a size close to the limit of photolithography. This embodiment will now be described with reference to FIGS. 2a to 2d.

FIG. 2a is a plan view showing a part of the first mask pattern M1, including a first opening AI formed in the X direction in the figure, and a first opening AI extending in the X direction from approximately the center. a second opening A2 at the end thereof, and a third opening A2 at the end thereof. These openings AI, A2. The width of A3 is set to a size 1, which is close to the photolithography limit of the 3g etching process, and the area indicated by the dotted line in the figure becomes a contact hole with minute dimensions, as will be described later. Note that as the mask material, a material such as a normal photoresist (regardless of the method used) can be used.

FIG. 2 is a plan view showing a part of the first mask pattern M11, including a first opening Bl formed in the Y direction in the figure and a second opening Bl arranged approximately in the center. , and a third opening B3 disposed on the right side in the figure. Each of these openings B1, B2. The width of B3 is similar to the width of each of the openings AI, A2, and A3 described above, and is set to a size l near the limit of photolithography of the relevant etching process, and the area indicated by the dotted line in the figure is as shown below. This results in a contact hole with minute dimensions. Note that as the mask material, a normal photoresist or the like can be used, and the mask material for the first mask pattern M1 and the mask material for the second mask pattern M- are different in material, film thickness, etching rate, etc. It can also be taken as a thing.

By combining the first mask pattern M1 and the second mask pattern M2, a pattern M3 as shown in FIG. 2C is obtained. This pattern M3 is the first
Each opening A1. of the mask pattern M1. A2. A3 and each opening Bl of the second mask pattern M2, B2 . B
The opening is only where it overlaps with 3. For details, see
The first opening A1 of the mask pattern M1 and the first opening A1 of the second mask pattern M2. Contact openings C1 and C2 are formed by overlapping the third openings Bl and B3, and the second opening A2 of the first mask pattern M1 and the second opening A2 of the second mask pattern M2 overlap. Third opening B2. B3 overlaps to form contact openings C3 and C4, and the first
The third opening A3 of the mask pattern M1 and the first opening B1 of the second mask pattern M2 overlap to form a contact opening C5. Furthermore, this pattern M3
The regions other than the contact openings Cl-C5 are formed by the mask pattern M1. Both or one of the M* mask materials will be coated.

When forming this pattern M3, the widths of the openings of the first and second mask patterns Ml and M2 are set to 8, respectively.
Since the size l is close to the photolithography limit of the etching process, the size of each of the contact openings 01 to C5 of pattern M3 is lxl, which is a contact hole with a size close to the photolithography limit. 1) easily.

FIG. 2d shows the first mask pattern M1 and the second mask pattern M1.
A pattern M consisting of a combination of mask patterns M2 of
Using 3, I? Contact holes DI, D2 .
D3. I)4. B5 is shown. These contact holes D1 to D5 are formed to reflect the contact openings Cl-C5, and each has a fine size IXI. Moreover, the corners are not rounded (formed), and by forming such a contact hole Di-D5 on a semiconductor device, it is possible to operate as designed even when miniaturization is attempted. It becomes possible.

The masking method of this embodiment is configured by combining the first mask pattern M1 and the second mask pattern M2 as described above, and in particular, each of the openings A1 to A3. B
Even when one interval of the openings is set to a size close to the limit value of photolithography, such as the width l of width l to B3, the interval of the openings in each longitudinal direction is from the limit value of photolithography mentioned above. It can be configured with plenty of leeway. Therefore, adverse effects such as fluctuations in exposure amount and single diffraction of light are alleviated by the first and second mask patterns Ml and M2, respectively, and the pattern M3, which is a combination of these first and second mask patterns, is This is close to the limit of photolithography, and it can easily become fine.

In addition, in the above-mentioned embodiment, each opening A1 to A3°Bl-
Although the shape of [33 is shown in the figure, it goes without saying that each mask pattern is not limited to the above shape, and may be any other pattern.

The contact hole is not limited to a square shape, and although the above embodiment describes an example of an etching process for forming a contact hole, it may also be applied to processing steps such as ion implantation or formation of a selective epitaxial growth layer. good.

Second Embodiment A masking method according to a second embodiment of the present invention utilizes the corner portions of the first mask pattern M1 and the corner portions of the second mask pattern No. to obtain a finer mask. be.

FIG. 3a shows a pattern M3 that is a combination of the first mask pattern M1 and the second mask pattern M2. The first mask pattern M1 has an opening A1, and the second mask pattern M1 has an opening A1.
The mask pattern M2 has an opening B1, and an area C1 where these openings A1.81 overlap becomes an area where the object to be processed is exposed. In this area CI, do the corners of the opening AI and the corner of the opening B1 overlap? Since it is in the iJY range, the size is even smaller than the limit value of photolithography. It can be iJT Jji.

Figure 3 shows an actual pattern that reflects the pattern M3, and if the sizes of the openings AI and Bl are close to the limit values of photolithography, the corners will be rounded to some extent. However, a sufficiently fine open pattern DI can be obtained on the object N to be processed.

H. Effects of the Invention The mask method of the present invention creates a pattern by intersecting a portion of the first mask pattern near the photolithography limit value and a portion of the second mask pattern near the photolithography limit value. Since it can be formed and used as a mask, it is possible to obtain an extremely fine pattern close to the limit value of photolithography. Therefore, by applying the present invention to semiconductor device manufacturing techniques, it is possible to easily manufacture fine semiconductor devices according to design values.

[Brief explanation of the drawing]

FIGS. 1a to taC are plan views for explaining the basic steps of an example of the mask method of the present invention according to the order of the steps, and FIGS. 2a to 2d are plan views of the first mask method according to the present invention. Figures 3a and 3121b are plan views for explaining the second embodiment of the present invention. Ml...First mask pattern M2...Second mask pattern M3...Pattern consisting of a combination...Limit value AI of photolithography, 82. A3...Opening B1, 82, 83...Opening Cl-C5 River contact opening D1-D5...Contact hole N...Processed object patent applicant Sony Corporation agent patent attorney Heavy oil inspection by Sakae Tamura - - to Σku1111 - 〉

Claims (1)

[Scope of Claims] A first mask pattern that is selective to the object to be processed is formed, and a pattern different from the first mask pattern that is selective to the object to be processed is formed on the first mask pattern. A masking method comprising: forming a second mask pattern having selectivity against the object; and applying a desired process to the object with a pattern consisting of a combination of the first and second mask patterns.