JPH0950113A - Halftone phase shift mask and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a halftone phase shift mask having light shielding patterns which suppress the sub-peaks of the light intensity to adversely affect image formation at the time of exposure without requiring the formation of ultrafine patterns and lower the transmittance in the regions to be multiple-exposed on the outer side of the element regions. SOLUTION: This hafltone phase shift film 202 exists on a transparent substrate 201. The patterns 207 which consist of the ultrafine particle films formed by blowing the gaseous ultrafine particles onto the substrate and shield the exposure light, are formed in the regions corresponding to multiple-exposed parts at the time of transfer of the mask on the transparent substrate 201.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a halftone phase shift mask and a method of manufacturing the same, and more particularly to a VLSI.
The present invention relates to a halftone phase shift mask that can be easily manufactured and can form a fine pattern among photomasks used for manufacturing the same, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A halftone phase shift mask is effective for forming a fine pattern, but has the following two problems. (1) At the time of transfer, there is a problem that a sub-peak of the light intensity is generated in the vicinity of the exposure pattern to be formed on the wafer, which deforms the exposure pattern to be originally generated. This problem is particularly prominent in the vicinity of a large void pattern, and in a large void pattern that can be sufficiently resolved without using the technique of phase shift lithography, the transfer characteristics are rather inferior to those of the conventional chrome mask.

(2) When the transfer exposure is sequentially performed by the stepper, there is a region where adjacent shots (ranges transferred by one exposure) overlap each other on the wafer. In the case of a conventional chrome mask, if you do not want to expose this multiple exposure area, leave the peripheral part of the mask as a pattern (black pattern)
If so, the exposure light was completely blocked and it was not exposed,
In the halftone phase shift mask, since the remaining pattern portion is also semitransparent, it is exposed by repeated multiple exposure.

That is, in the halftone phase shift mask, it has been practically necessary to provide a partial area on the substrate with a light shielding property. For this purpose, one of the following two methods has been conventionally used. (A) A method of arranging an ultrafine repetitive pattern below the resolution limit in a mask region where it is not desired to transmit exposure light (JP-A-6-175347). (B) A halftone phase shift film and a light-shielding film or a film capable of obtaining high contrast are laminated, and after the whole is processed into a predetermined pattern, a light-shielding film or a film capable of obtaining high contrast is required. How to process into a pattern.

[0005]

[Problems to be Solved by the Invention] The above solution (A)
Has the advantage that a mask can be produced by a single lithographic process, but the repeating pattern described above must be extremely fine, and it was very difficult to form this. Further, although the solution (B) is easy to form a pattern, there is a problem in that it is essentially necessary to perform the plate making twice, and the process becomes long.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to eliminate the need for forming an ultrafine pattern and to have a light intensity which adversely affects image formation during exposure. (EN) Provided are a halftone phase shift mask having a light-shielding pattern which suppresses the sub-peak of (1) and which has a reduced transmittance in a region where multiple exposure is performed outside the element region, and a manufacturing method thereof.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been studied to achieve the above object, and as a result, in the region where the above light shielding property is required,
It was completed by finding that the problem can be solved by forming a pattern composed of an ultrafine particle film.

That is, a region outside the element region, which is double or more exposed in step and repeat exposure,
By forming an ultrafine particle film in a region or the like which can be resolved without utilizing the halftone phase shift effect in the element region, it is possible to enhance the light shielding property in these regions. This ultrafine particle film is formed by spraying ultrafine particles on a substrate,
Since it can be formed by post-treatment, a lithography process is not required.

FIG. 1 shows the structure of a commercially available apparatus for forming an ultrafine particle film. This apparatus is used in the ultrafine particle generation chamber 101.
And a film forming chamber 102. These two chambers are connected by an ultrafine particle transport pipe 103 and partitioned by a valve 104. Vacuum can be evacuated by the two-chamber exhaust pumps 105 and 106, and an inert gas such as argon can be introduced into the ultrafine particle generation chamber 101 through the valve 107. The raw material for the ultrafine particles is the heating boat 1 in the ultrafine particle generating chamber 101.
Set within 08. The substrate on which the ultrafine particle film is formed is set on the XY stage 109 in the film forming chamber 102.

Using this apparatus, an ultrafine particle film is formed as follows. With the valves 104 and 107 closed, the ultrafine particle generation chamber 101 and the film formation chamber 102 are connected to the vacuum pump 10.
A vacuum is drawn at 5, 106. Then, the valve 107 is opened and an inert gas is introduced into the ultrafine particle generation chamber 101.
By heating the material in the raw material boat 108 in this state, ultrafine particles are generated. The amount and particle size of ultrafine particles produced can be controlled by controlling the amount of inert gas introduced, the pressure in the ultrafine particle production chamber 101, the evaporation rate of the material, and the like. When the valve 104 is opened when the generation of the ultrafine particles is stabilized, the ultrafine particles are transferred to the film forming chamber 102 through the ultrafine particle transport pipe 103 due to the pressure difference between the two chambers, pass through the nozzle 110 at the tip thereof, and pass through the X-axis. -It is sprayed onto the substrate on the Y stage 109. Here, by moving the XY stage 109 while controlling it, a pattern of an arbitrary ultrafine particle film can be formed on the substrate.

As the ultrafine particle material capable of forming the ultrafine particle film, metal materials such as gold, copper, tin, iron, chromium and nickel are generally used. Also, other metal films, alloy films,
Ceramic membranes and the like are also conceivable.

The ultrafine particle film formed by this method is
Since it is possible to form a pattern without a lithography process and has a sufficient light-shielding property, when applied to a halftone phase shift mask, all of the above problems can be solved.

The above-mentioned conventional solutions (A) and (B)
It is also possible to use together with. Further, the method of the present invention can be adopted not only in the above-mentioned problem area but also when it is necessary to reduce the transmittance for other reasons.

As is clear from the above description, the halftone phase shift mask of the present invention is a halftone phase shift mask having a halftone phase shift film consisting of a single layer or two or more layers on a transparent substrate. In a part of the transparent substrate, a pattern made of an ultrafine particle film for blocking exposure light is formed.

In this case, the region in which the pattern made of the ultrafine particle film is formed is the mask peripheral region including the region corresponding to the multiple exposure portion at the time of transfer of the halftone phase shift mask, or the halftone phase shift effect. It is the peripheral part of the pattern that can be resolved without being referred to.

Further, such a halftone phase shift mask is manufactured by forming an ultrafine particle film by spraying gaseous ultrafine particles onto a substrate.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The halftone phase shift mask according to the present invention is a halftone phase shift mask having at least a halftone phase shift film on a transparent substrate, in which a pattern made of an ultrafine particle film is formed in a partial region. It is what Hereinafter, an embodiment of the present invention for forming a so-called light-shielding band for preventing exposure of the multiple-exposure portion during transfer of the halftone phase shift mask will be described with reference to the drawings showing the manufacturing process of FIG. As shown in FIG. 2A, a deep ultraviolet (DU) was formed on a 6-inch square, 0.25-inch thick synthetic quartz substrate 201 for photomask under the following conditions.
V) forming a halftone phase shift film 202 for exposure,
Halftone phase shift mask blank 2 for DUV exposure
Get 03.

Deposition method: DC magnetron sputtering target: Metal chromium Deposition gas and flow rate: Argon 75 sccm + Carbon tetrafluoride 25 sccm Deposition pressure: Approx. 4 mTorr Current: 5 amperes Note that the refractive index and the extinction of the film 202 at a wavelength of 250 nm. The extinction coefficients are 1.7 and 0.27, respectively. Therefore, the film thickness required for the DUV exposure phase shift film is about 185 nm. Further, when the above-described film 202 was formed on the quartz substrate 201 by about 185 nm, the transmittance thereof was about 10% when the transparent substrate was 100%.

Next, as shown in FIG. 2B, an electron beam resist 204 is applied on the blank 203 and patterned by an ordinary electron beam lithography method, as shown in FIG. Then, the resist pattern 205
Get. Using this resist pattern 205 as a mask, the halftone phase shift film 202 whose surface is exposed is dry-etched under the following conditions.

Etching method: High frequency reactive ion etching Gas and flow rate: Dichloromethane 20 sccm + Oxygen 50 sccm Pressure: About 300 mTorr Power: 250 W After the above etching is completed, the resist pattern 205 is removed, and DUV exposure as shown in FIG. 2D is performed. To obtain a halftone phase shift mask 206 for use.

Next, in order to form a so-called light-shielding zone in the peripheral portion, the ultrafine particle film manufacturing apparatus shown in FIG. 1 is used, and it is a region outside the element region where substantially no halftone phase shift effect is required. , With step and repeat exposure 2
As shown in FIG.
The ultrafine particle film 207 was formed as follows.

In the ultrafine particle film producing apparatus, the ultrafine particle Fe film 207 is produced under the following conditions. Raw material boat 1
Fe chunk (lump) as a raw material is placed on 08, the vacuum pump 105 evacuates the ultrafine particle generation chamber 101, and subsequently, the valve 107 is opened to open the ultrafine particle generation chamber 10.
Helium gas is introduced so that the pressure in 1 becomes about 300 Torr. At the same time, the film forming chamber 102 has a vacuum pump 10
A vacuum is drawn to 10 mTorr or less by 6. Next, the valve 104 is opened to move from the ultrafine particle generation chamber 101 to the film formation chamber 1
Create a flow of gas towards 02. At this time, an electric current is passed through the raw material boat 108 to heat the Fe chunk so that it is just above the evaporation temperature of Fe (about 1550 ° C.), so that the raw material becomes ultrafine particles by so-called vapor deposition in gas,
The gas flow is carried to the film forming chamber 102.

In this embodiment, the tip diameter of the nozzle 110 at the tip of the ultrafine particle transport pipe 103 is set to 300 μm. At this time, an ultrafine particle film having a width of about 200 μm is formed on the substrate. Since the film forming speed under this condition is about 20 μm / sec, which is considerably high, even if the substrate is scanned at high speed by the XY stage 109, the ultrafine particle film 2 having a sufficiently high light shielding property is obtained.
07 could be formed.

The ultrafine particle film formed by this method is
Adhesion to the substrate is good, and it does not peel off in the scrub cleaning process when cleaning the photomask. Also,
In this embodiment, the Fe film is formed, but this is an example.
Films of various metals such as chromium, gold, copper, tin, nickel and alloys thereof can be formed.

Although the halftone phase shift mask of the present invention and the method for manufacturing the same have been described above based on the embodiments, the present invention is not limited to these embodiments and various modifications can be made.

[0026]

As is apparent from the above description, according to the halftone phase shift mask and the method for manufacturing the same of the present invention, a pattern made of an ultrafine particle film that shields exposure light in a partial region on the transparent substrate. It is not necessary to form an ultra-fine pattern by only forming the film, suppressing the sub-peak of the light intensity that adversely affects the image formation during exposure, and the transmittance in the multiple-exposed area outside the element area. A halftone phase shift mask having a lowered so-called shading band can be easily obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an apparatus for forming an ultrafine particle film in the present invention.

FIG. 2 is a diagram showing steps of a method of manufacturing a halftone phase shift mask according to one embodiment.

[Explanation of symbols]

 101 ... Ultrafine particle generation chamber 102 ... Film formation chamber 103 ... Ultrafine particle transport pipe 104 ... Valves 105, 106 ... Vacuum pump 107 ... Valve 108 ... Heating boat 109 ... XY stage 110 ... Nozzle 201 ... Synthetic quartz substrate 202 ... Half Tone phase shift film 203 ... Halftone phase shift mask blank 204 ... Electron beam resist 205 ... Resist pattern 206 ... Halftone phase shift mask 207 ... Ultra fine particle film

Claims (4)

[Claims] 1. A halftone phase shift mask having a halftone phase shift film composed of a single layer or two or more layers on a transparent substrate, wherein an exposure light made of an ultrafine particle film is formed on a part of the transparent substrate. A halftone phase shift mask, which is characterized in that a pattern for shielding light is formed. 2. A mask peripheral portion including a region corresponding to a multiple exposure portion at the time of transfer of a halftone phase shift mask, wherein the region in which the pattern made of the ultrafine particle film is formed. The described halftone phase shift mask. 3. The half according to claim 2, wherein the region in which the pattern made of the ultrafine particle film is formed is a peripheral portion of the pattern which can be resolved without the halftone phase shift effect. Tone phase shift mask. 4. The method of manufacturing a halftone phase shift mask according to claim 1, wherein the ultrafine particle film is formed by spraying gaseous ultrafine particles onto the substrate. .