JPS63157421A - Method of forming resist pattern - Google Patents

Abstract

PURPOSE:To obtain a pattern exceeding the resolution of an exposing equipment, by a method wherein a negative type resist pattern is subjected to exposure and development by applying a fine positive type resist pattern to a light- shielding mask, and a part which is not yet exposed under the fine light- shielding mask is eliminated CONSTITUTION:A base film 11 composed of SiO2 and the like is arranged on a substrate 10, and a resist film 11 sensitized to ultraviolet rays is formed. A positive type resist film 13 sensitized to ultraviolet rays is formed on the film 12. Exposure 11 is performed toward the film 15 by an exposing equipment, and then the film is developed to form an aperture 15 in which the surface of the film 12 is exposed and a positive type resist pattern 10 of a part which is not yet exposed. The whole part of the pattern 16 is irradiated by far ultraviolet rays applying a pattern 18 to a light-shielding mask./ Thereby, the aperture part 15 is exposed to light in the film 12. By developing, a lower part of the pattern 16 as a part of the film 11 which is not yet exposed is eliminated, and a negative type resist pattern 18 of the exposed part of the film 12 is formed, By making intervals of the pattern 18 very small, a pattern is obtained which exceeds the resolution of the exposing equipment.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is a semiconductor device! The present invention relates to a resist pattern forming method in a photolithography step in the manufacturing process of Cμ (also referred to as LSI).

(Prior art) In the conventional photolithography process using ultraviolet light (G line, 1 line), a photoresist film made of an organic material is used as an etching mask for a film to be etched using an exposure device such as a reflection projection or a reduction projection. This photoresist has two types: a positive type in which the exposed portion is removed during development, and a negative type in which the unused portion is removed during development. As shown in Figure 2, the dimension of the tectonic pattern changes with the dose of exposure energy. In Figure 2, P is positive type, N
is a negative resist film, M is a mask dimension, and as the dose 1 increases, the change in pattern dimension with respect to the dose becomes smaller and becomes stable. Therefore, the desired pattern dimensions of the entire putter.

In order to form in a stable region, it is necessary to increase the dori and take into account the variation in the resist size of the semiconductor urchin 2,- with respect to the mask size.

FIG. 3 is a diagram illustrating a conventional method for forming a resist pattern using a photoresist film.

In the figure, 5i02 oxide@2 is formed on a Sl substrate 1, and a positive type photoresist FA3iE having a uniform thickness is formed thereon by a spin code method or the like. Using this ultraviolet light (using the exposure device in state Q), the photoresist @3 is exposed in a pattern in the stable region shown in Figure 2, and the exposed portion of the photoresist film 3 is removed by development as shown in (b). do.

In this case, if the width of the photoresist strip 3 to be removed by buttering exceeds the resolution of the exposure apparatus, for example, 0.8 μm, there is no problem as shown in (b). However, 0.8 μm
[If it is below, the photoresist film 3 is formed by diffraction development of ultraviolet light.
The portion that should originally be exposed remains unexposed, and when this is developed, the photoresist film 3 becomes sagging as shown in (C). In this state, as shown in (b) to (d), it is no longer possible to stably form, for example, a contact hole by removing the oxide 11112 to a predetermined width using an extender liquid or the like.

FIG. 4 shows a photomask used in photolithography. In the figure, a chrome pattern 5t is formed under a glass (blank) 4.

As shown in (a), the distance between the chrome patterns 5 is Ll.
As long as the light intensity curve is as large as 01, it is possible to obtain the contrast of a sumo wrestler. If it becomes small, the light intensity curve becomes like C2, and it becomes impossible to obtain sufficient contrast. Furthermore, even if the line width of the chrome pattern is reduced to L2, it is also impossible to obtain sufficient contrast.

(Problem to be solved by the invention) However, regardless of the method described above, the LS
Due to the high integration of I and the miniaturization of setanes, the removal width of the resist film on the film to be etched must also be made minute. When the width becomes narrower, a diffraction phenomenon of ultraviolet light occurs, and the contrast on the resist film due to the photomask also decreases, and the distance between the resist patterns is t-1! It was impossible to narrow the resolution below that of the original device, and it was not possible to obtain a technically satisfactory resolution.

It is an object of the present invention to provide a method for forming a pattern with excellent resolution, which eliminates the above-mentioned problems in that the spacing between patterns cannot be made completely fine.

(Means for Solving the Problems) In the resist pattern forming method according to the present invention, a negative resist wedge and a positive resist wedge are formed in a two-layer structure on a film to be etched/etched, and a positive resist film k' This positive resist pattern is turned, developed, and then developed by passing light through the exposed gold negative resist film as a mask for the entire positive resist pattern.

(Function) The 4-turn forming method in this invention involves exposing and developing a high-resolution positive resist film TL to obtain fine positive resist neutral turns,
) Using the pattern as a light-shielding mask, expose and develop the negative resist pattern to expose the unexposed area f+ under the fine light-shielding mask.
By removing the negative resist, the interval between the nine turns of the negative resist is reduced to a fine φ, and a resolution higher than that of the 31-element device is obtained.

(Example) Below, an example of the present invention will be described based on the drawings. 1st
The figure shows a process sequence according to an embodiment of the present invention. In the same figure, in (a), a base @11't- is formed on a semiconductor substrate 81 substrate 10;
Examples include 5in2fly, polysilicon film, and aluminum film. For example, on this base Th1l, a wavelength of 2000 A to 3 is used, such as chloromethyl polystyrene.
After applying a negative resist sensitive to deep ultraviolet rays of 0.000A to a uniform thickness of 5000A to 12000A using a spin coating method, it was coated on a hot plate in air for about 100A.
Gribake is performed for about 100 seconds at 20'CT to form a 781' type Resost film.

Next, as shown in (b), on the negative resist film 12, for example, a phenol novolac or the like is applied as a main component with a torsion wavelength of 400.
A positive resist sensitive to ultraviolet rays of 0A to 4500A is applied by spin coating to a uniform thickness of 8000A to 1200OA, and then prebaked on a hot plate in air at about 100°C for about 100 seconds. High resolution positive resist il.

Fully formed.

Next, as shown in (e), a positive resist a! is applied from above.
The positive resist film 1 is exposed to ultraviolet light (wavelength 4000A to 4500A) in a predetermined /J pattern 113 using an exposure device (not shown), and then developed as shown in (d) to form a positive resist film 1.
The exposed portion t of No. 3 is removed to completely form the opening 15 in which the surface of the negative resist 120 is exposed and the positive resist pattern 16 in the unexposed portion.

In this step, the width of the opening 15 exceeds the resolution of the g-light device, and the ultraviolet rays 14 do not cause diffraction, so the boundary between the opening 15 and the positive resist pattern 216 is clear. Then, set the width of the positive resist 2 turn 16 to about 0.
It can be easily formed to a thickness of 3 μm to about 0.5 μm.

Next, as shown in (e), a positive resist film fi-71
Far ultraviolet rays (wavelength 2000A ~) using 6 as a light-shielding mask
3000A) Full-surface exposure is performed in step 17 to expose the area of the opening 15 within the negative resist film 12. after that,(
As shown in f), a positive type dust pattern 16 and a negative type are developed by developing with a developer consisting of a mixture of acetic acid inamyl alcohol and ethylcerene lubricant or a solution of methyl isobutyl ketone, methyl ether ketone, etc. ml 2
The portion below the $'-type resist pattern 16, which is the unexposed portion of the resist pattern 16, is removed to form a negative resist pattern 18, which is the original part of the negative resist @12. A recess 19 is formed between the negative resist patterns 18 and has a width of, for example, 0.3 μm to 0.5 μm below the resolution μ of the exposure apparatus.

Next, as shown in (g) VC, negative resist pattern 1
8 as a mask, fine lines or holes 20 are formed in the underlayer 11 by etching, and the negative resist pattern 18 is completely removed, as shown in the figure below.

For example, the line or hole 20 is approximately 0.3 to 0.54□
A contact hole in the mouth can be formed.

As described above, according to the present invention, by using a negative resist with high resolution as the lower layer, a setter 7 which is inverted with respect to the positive resist pattern can be obtained.
By increasing the amount of light in the positive resist pattern, it is possible to stably form extremely fine patterns, and the pattern size is not limited by the resolution limit of the exposure equipment, for example. G-1ine N, A O
, 35 STAY A-TE is also capable of forming a pattern of 0.3 to 0.5 μm. Therefore, the small slope slit of the negative resist pattern obtained by inverting this fine pattern becomes an extremely narrow slit or contact hole that is larger than the resolution of the above-mentioned binding device.

(Effect of the invention) As described above, according to the manufacturing method of the present invention, the resist I
The ViI is formed into a two-layer structure of a negative type and a positive type, and the resist film is exposed and exposed from the positive type to the negative type 11, so that the slit of the turn of the resist can be formed with a resolution higher than that of the exposure equipment. It is possible to form a complete LSI, and it is possible to increase the degree of integration of LSI, and it is expected that it can be made at low cost without requiring special equipment such as XIL or electron beam.

[Brief explanation of the drawing]

Fig. 1 is a process diagram according to an embodiment of the present invention, Fig. 2 is a diagram showing the relationship between dose amount and arm turn dimension, Fig. 3 is a process diagram of a conventional pattern forming method using tarry, and Fig. 4 is an explanatory diagram showing the relationship between a photomask and a light intensity curve. 10...Semiconductor substrate, 11...Etching test, 1
2... Negative resist film, 13... Positive type Lusosto m, 14... Ultraviolet light, 16... Positive resist film, 17... Far ultraviolet light, 18... Negative resist pattern. 1S Figure 3

Claims (1)

[Claims] (1) A first step of forming a negative resist film on the film to be etched provided on the surface of the semiconductor substrate, and then a second step of forming a positive resist film on the negative resist film.
Step, Next, a third step of patterning the positive resist film, Next, a fourth step of developing the positive resist film using a first developer to form a positive resist pattern. Next, the entire surface is exposed using the positive resist pattern as a light shielding mask, and the negative resist film is exposed in a fifth step.
a sixth step of developing the negative resist film using a second developer and removing the unexposed portion of the negative resist film together with the positive resist pattern to form a negative resist pattern; A resist pattern forming method comprising the steps of: