JP3445329B2 - Halftone type phase shift mask and halftone type phase shift mask blank - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase shift mask capable of improving the resolution of a transfer pattern by giving a phase difference between exposure lights passing through the mask,
The light-shielding part is made up of a semi-transparent film that transmits light of an intensity that does not substantially contribute to the exposure and at the same time shifts the phase of the transmitted light, and the lights that have passed near the boundary between the light-shielding part and the light-transmitting part cancel each other out. The present invention relates to a so-called halftone type phase shift mask and a halftone type phase shift mask blank, which is a material thereof, capable of appropriately maintaining the contrast of a boundary portion.

[0002]

2. Description of the Related Art In manufacturing a semiconductor LSI, a phase shift mask is used as one of photomasks which are fine pattern transfer masks. This phase shift mask, by giving a phase difference between the exposure light passing through the mask,
The resolution of the transfer pattern can be improved. As one of the phase shift masks, the phase shift mask described in Japanese Patent Laid-Open No. 4-136854 is known as a mask suitable for transferring an isolated pattern such as a single hole, dot or line, and space. There is.

FIG. 23 is a sectional view of a phase shift mask disclosed in Japanese Patent Laid-Open No. 4-136854. As shown in FIG. 23, the phase shift mask 30 described in this publication is
A semi-transparent film 32 is formed on the transparent substrate 31 to transmit light having an intensity that does not substantially contribute to exposure and at the same time shifts the phase of light passing therethrough. Then, the transfer region I in the central portion of the transparent substrate 31 is formed. In addition, by selectively removing a part of the semi-translucent film 32, the translucent portion 33 that transmits the light having the intensity that substantially contributes to the exposure and the light having the intensity that does not substantially contribute to the exposure are transmitted. The mask pattern formed by the semi-transparent portion 34 is formed. The phase shift mask 30 shifts the phase of the light passing through the semi-transparent portion 34 so that the phase of the light passing through the semi-transparent portion 34 is different from the phase of the light passing through the transparent portion 33. The light beams that have passed through the vicinity of the boundary between the light-transmitting portion 33 and the semi-light-transmitting portion 34 and are circulated by the diffraction cancel each other out. The contrast is kept good. FIG. 24 shows an amplitude distribution and an intensity distribution of light that has passed near the boundary between the light transmitting portion 33 and the semi-light transmitting portion 34. This type of phase shift mask is called a so-called halftone type phase shift mask.

[0004]

As described above, the halftone type phase shift mask is essentially a semitransparent portion that has both a phase shift function and a light shielding function. That is, the semi-transmissive portion functions as a phase shift layer at the boundary of the pattern and as a light shielding layer at the other portions. Therefore, a small amount of leaked light reaches the portion where it is ideal to completely block the exposure light. Normally, the total exposure amount is adjusted so that even if the leaked light is present, the exposure is not substantially achieved.

By the way, for example, as in the case where the film thickness of the resist to be exposed formed on the transferred material is largely different depending on the location, the required exposure amount is largely different depending on the location of the transferred material. In such a case, the total exposure dose must be set to a value that can cover the maximum exposure dose of the exposure doses required at each position of the transferred body. Otherwise, the entire exposure will not be possible.

However, in this case, for example, in a thick film portion requiring a large exposure amount, the influence of light leaked from the semi-translucent portion is small, but in a thin film portion, development is performed by exposure to leak light. It has been found that the case where the film thickness of the resist later exceeds the allowable range may occur. 25 to 27 are explanatory diagrams of this situation.

FIG. 25 is a diagram showing an example of a transferred material in which the film thickness of the resist to be exposed differs depending on the location, and FIG. 26 is shown in FIG.
5 is a diagram showing a state in which the transferred material of No. 5 is exposed, and FIG.
FIG. 7 is a diagram showing a transferred material after being exposed and developed as shown in FIG.

The transfer target shown in FIG. 25 is a substrate 100.
A conductive film 101 having a step of about 0.5 μm is provided thereon, and a positive resist film 102 for pattern formation is formed thereon by spin coating. This transferred material is obtained by pattern-exposing and developing the resist 102 to form a resist pattern, and then performing etching using the resist pattern as a mask to form a wiring pattern on the conductive film 101.

As shown in FIG. 26, the exposure of the resist film 102 is performed by a halftone type phase shift mask 30.
Consider when to do by. In this case, the film thickness of the resist 102 in the region B where the conductive film 101 is thin is larger than the film thickness of the resist 102 in the region A where the conductive film 101 is thick. Therefore, the value of the exposure amount is set to a large value capable of exposing the area B.

Then, as shown in FIG. 27, when the resist 101 is developed, the resist pattern 102a is thinned in accordance with the leaked light from the semi-transparent portion 34.
This amount of film reduction is not an amount that causes a problem at the time of etching in a region B where the film thickness of the resist film 102 is originally sufficiently thick. However, in the region A where the film thickness of the resist film 102 is originally thin, the film thickness may be further reduced, and the function as a mask may not be sufficiently fulfilled during etching. Therefore, it becomes difficult to set the exposure amount, and in some cases, the optimum exposure amount may not be obtained. This situation becomes a particularly serious problem when the transmittance of the semi-translucent portion is high (for example, 10 to 15%), because the amount of energy leakage of the exposure light increases.

Further, this halftone type phase shift mask is a mask (reticle) of a reduction projection exposure apparatus (stepper) which is an exposure apparatus usually used for semiconductor manufacturing.
Used as. This stepper reduces the projection image obtained by projecting the reticle with exposure light using a projection lens,
Reduction projection exposure is performed by forming an image on a semiconductor wafer that is a transfer target. In this reduction projection exposure, usually, the pattern of the same reticle is repeatedly transferred and exposed at different positions on one semiconductor wafer, and a large number of semiconductor chips are obtained from one wafer. Therefore, when pattern transfer is performed using this stepper, as shown in FIG. 23, only the transfer region I of the phase shift mask 30 (reticle) is exposed by the covering member (aperture) 36 provided in the stepper. Thus, the peripheral area is covered and exposed.

However, this aperture 36 is
It is difficult in terms of mechanical precision to set up so that only the transfer area is exposed with high accuracy (for example, accuracy of 1 μm or less), and in many cases, the exposed portion is exposed in the non-transfer area around the outer periphery of the transfer area. Even if the aperture has a high precision and there is no protruding portion, the exposure light is diffracted and reaches the non-transfer area because of the distance between the aperture and the transfer target.

As described above, when the aperture 36 allows the exposure light to pass through a wider area than the original transfer area, the following problems have been found. That is, the halftone type phase shift mask 30 normally has a light semi-transmissive film 32 that allows light of intensity not substantially contributing to exposure to pass through the non-transfer region.
Are formed. For this reason, as described above, when the aperture 36 allows the exposure light to pass over a wider area than the original transfer area, the exposed portion is exposed by light having an intensity that does not substantially contribute to the exposure. Of course, even if there is the protruding portion, no problem occurs in one exposure. However, this overexposed portion (exposed exposed portion) may overlap the transfer area, or may overlap with the exposed portion in the same manner during the next exposure. In exposure, even if the exposure amount does not substantially contribute to the exposure, they may be added to reach the amount that contributes to the exposure. Therefore, this causes the same effect as the case where the area which should not be exposed originally is exposed, resulting in a defect. Hereinafter, this point will be specifically described.

FIG. 28 is an explanatory view showing a phenomenon in which the exposed portions overlap each other. In order to simplify the description, FIG. 9 assumes a case where four transfer are performed adjacently on a wafer coated with a resist as an exposure target, and areas EI1, EI2, EI3 surrounded by solid lines are shown. EI4 is the transfer region, and the portions surrounded by the dotted lines outside the respective transfer regions are the protruding portions .DELTA.EI1, .DELTA.EI2, .DELTA.EI3 and .DELTA.EI4. The dimensions (vertical and horizontal) of each transfer area are I, the dimensions (vertical and horizontal) of the light passage holes of the actual aperture are I ′, and the dimension (width) of the protruding portion is ΔI. The transfer area EI
The mutual positional relationship of 1, EI2, EI3, and EI4 is set so as to be accurately aligned with each other by the XY stage of the stepper. Further, in FIG. 28, in order to make the explanation easy to understand, the protruding portions ΔEI1, ΔEI2, and ΔE
I3 and .DELTA.EI4 are shown enlarged.

As is apparent from FIG. 28, the protruding portion Δ
EI1, .DELTA.EI2, .DELTA.EI3, and .DELTA.EI4 are adjacent to each other, and an overlapping portion occurs between them. These overlapping portions are respectively defined as δEI12, δEI24, δEI34, δEI13,
If δEI234, δEI134, δEI123, δEI124, the overlapping portions δEI12, δEI24, δEI34, δE
The number of overlaps of I13 is two, but the overlap portion δE
I234, δEI134, δEI123, and δEI124 are three times, and further, at the point O, they are substantially four times of overlap. Now, assuming that the light transmittance of the semi-translucent film 32 is 15%,
The same amount of exposure as when passing through a film with a light transmittance of 30% was applied to the double-overlap portion, and the light transmittance was 45% for the triple-overlap portion.
That is, the same amount of exposure as that when passing through the film of No. 4 is performed, and the same amount of exposure as when passing through the film having the light transmittance of 60% is performed at the overlapped portion four times. For this reason, in these overlapping portions, there are cases in which the exposure reaches the intensity that substantially contributes to the exposure. As a result, after performing this exposure, the resist is developed, and on the wafer on which a pattern is formed by performing predetermined etching or the like, an unnecessary pattern is formed in a portion that should not be originally formed,
A pattern defect will occur.

The present invention has been made under the above-mentioned background, and with a relatively simple structure, while taking full advantage of the original advantages of the halftone type phase shift mask, the drawback of exposure light leakage is almost completely eliminated. It is an object of the present invention to provide a halftone type phase shift mask capable of preventing the above and a halftone type phase shift mask blank as a material thereof.

[0017]

In order to solve the above problems, the halftone type phase shift mask of the present invention is (Structure 1) a mask for transferring a fine pattern, which is formed in a transfer region on a transparent substrate. The mask pattern has a light-transmitting portion that transmits light having an intensity that substantially contributes to exposure and a semi-light-transmitting portion that transmits light that does not substantially contribute to exposure. By shifting the phase of the light passing therethrough to make the phase of the light passing through the semi-transparent portion different from the phase of the light passing through the transparent portion, the boundary between the transparent portion and the semi-transparent portion is changed. In a halftone type phase shift mask capable of maintaining good contrast at a boundary portion by utilizing a canceling effect of light passing through the vicinity, at least in the mask pattern transfer region, at least in the mask pattern transfer region, the light transmitting portion and the semitransparent portion. Near the boundary with the light section Definitive canceling action of light in a structure, characterized in that it comprises a light shielding layer on or below the substantially do not contribute semi-light-transmitting portion, as an aspect of this configuration 1, (Structure 2) mask for transferring a fine pattern And
The mask pattern to be formed in the transfer area on the bright substrate
And a light-transmitting part that transmits light of the intensity that contributes to the exposure
And a semi-translucent part that transmits light of intensity that does not contribute to the exposure
And shift the phase of the light passing through this semi-transmissive part.
And the phase of the light passing through the semi-transparent portion and the light passing through the transparent portion.
By changing the phase of the light,
Utilizing the canceling effect of light that has passed near the boundary with the semi-transparent part
So that the contrast at the boundary can be maintained well
In the halftone type phase shift mask, at least
On the semi-transparent portion in the mask pattern transfer area or
There is a light-shielding layer below, and the light- shielding layer is a region of the semi-light-transmitting portion.
Exposure light in the vicinity of the boundary between the light-transmitting part and the semi-light-transmitting part
Of exposure light passing through the region that contributes to the offsetting effect of
The light intensity above is smaller than that without the light-shielding layer.
A structure characterized by being provided in a region including a region to be
Then, as an aspect of the constitution 1 or the constitution 2, (constitution 3) in the Hartoon type phase shift mask of constitution 1 or constitution 2, the non-transfer region adjacent to the boundary between the mask pattern transfer region and the non-transfer region is semi-transparent And a light-shielding layer having a predetermined width or more is provided in the semi-translucent portion of the non-transfer area.

Further, the halftone type phase shift mask blank according to the present invention is (Structure 4) Halftone type phase shift mask used as a material for manufacturing the halftone type phase shift mask of any one of Structures 1 to 3. A mask blank having a semi-transparent film forming a semi-transparent portion on a transparent substrate, and having a light-shielding film forming a light-shielding layer above or below the semi-transparent film. It was configured. Furthermore, according to the present invention
The mask pattern transfer method is (Structure 5)
Pattern transfer to the substrate to be transferred using
The configuration is characterized in that the images are taken.

[0019]

According to the above configuration 1, the light is shielded at least in the mask pattern transfer region and in the semi-transparent portion that does not substantially contribute to the canceling action of the light in the vicinity of the boundary between the translucent portion and the semi-transparent portion. By providing the layer, it is possible to suppress the exposure light from leaking at that portion. Therefore, the film loss of the resist can be reduced. In this case, the pattern accuracy of the mask pattern is determined by the pattern accuracy of the semi-transparent portion, and the pattern accuracy of the light-shielding layer and the thickness accuracy thereof are not so required, so that the design and formation thereof are relatively easy. Therefore, it is possible to almost completely prevent the leakage of exposure light, which is a drawback thereof, while utilizing the original advantages of the halftone type phase shift mask. Moreover, according to the above configuration, the light intensity of the exposure light passing through the light transmitting portion on the non-transfer substrate is higher than that of the conventional one, and the light transmitting portion and the semi light transmitting portion are in the area of the semi light transmitting portion. It has been confirmed that the light intensity on the non-transfer substrate of the exposure light that has passed through the area near the boundary with the part and that does not contribute to the offsetting effect of the exposure light is smaller than before, and the actual effect of improving the contrast of the transfer pattern. Has been confirmed to be significant.

Further, according to the structure 2, the non-transfer area adjacent to the boundary between the mask pattern transfer area and the non-transfer area is a semi-transmissive portion, and the semi-transmissive portion of the non-transfer area has a predetermined amount or more. By providing a light-shielding portion having a width of, when this halftone type phase shift mask is used as a stepper reticle, the stepper aperture light passing area and the reticle halftone phase shift mask transfer area are provided. Even if the exposure light is projected to the semi-transmissive part in the non-transfer area of the phase shift mask and is irradiated with the exposure light, the exposure light projected from the projection is blocked by the light shielding part and transmitted. Can not do it. As a result, it is possible to completely prevent unnecessary exposure light from reaching the non-transfer area on the transfer medium, and there is a slight deviation between the light passage area of the aperture and the transfer area of the halftone phase shift mask. In this case, it is possible to prevent the occurrence of exposure defects due to this shift.

Further, according to the constitution 3, a halftone type phase shift mask blank which can easily manufacture the halftone type phase shift mask of the constitution 1 or 2 is obtained.

[0022]

【Example】

(Embodiment 1) FIG. 1 is a diagram showing a structure of a halftone type phase shift mask according to Embodiment 1 of the present invention. FIG. 2 is an end view taken along the line II of FIG. 2, and FIG. Plan views of the halftone type phase shift mask, FIGS.
FIG. 3 is an explanatory diagram of a manufacturing process of the halftone phase shift mask according to the first embodiment. Example 1 will be described below with reference to these drawings. The halftone type phase shift mask blank is a material used for manufacturing the halftone type phase shift mask, and has at least a semitransparent film forming a semitransparent portion on a transparent substrate. Since the one having the light-shielding film forming the light-shielding layer above or below the light film is widened, its configuration will be clarified in the section of the manufacturing process of the halftone type phase shift mask, and the description thereof will be omitted. To do.

In FIGS. 1 and 2, reference numeral 1 is a halftone type phase shift mask, reference numeral 2 is a transparent substrate, reference numeral 3 is a low transmittance layer, reference numeral 4 is a high transmittance layer, and reference numeral 5 is a semitransparent layer.
Reference numeral 6 is a light transmitting portion, and reference numeral 7 is a light shielding layer.

The halftone phase shift mask 1 has a patterned semi-transmissive layer 5 formed by removing a part of a film formed on the entire surface of the transparent substrate 2 to form a translucent portion 6.
And a light-shielding layer 7 is formed on the main part of the semi-translucent layer 5 except for the vicinity of the boundary with the translucent part 6.

The semi-translucent layer 5 is formed by superposing a high transmittance layer 4 which mainly controls the phase shift characteristics on a low transmittance layer 3 which mainly controls the light transmittance characteristics.

The light transmitting portion 6 is a portion that transmits light having an intensity that substantially contributes to exposure. Further, the semi-translucent layer 5 is a portion that transmits light having an intensity that does not substantially contribute to exposure, and at the same time, the phase of the light passing through the semi-translucent layer 5 is shifted to shift the phase of the semi-translucent layer 5. By making the phase of the light passing through and the phase of the light passing through the translucent portion 6 different from each other, the canceling action of the light passing near the boundary between the translucent portion 6 and the semi-translucent layer 5 is utilized to make a boundary. This is to make it possible to maintain good contrast of the part.

Area I is a transfer area, and the other areas are non-transfer areas. Further, the region I ′ is a light passage region of the stepper aperture when the halftone type phase shift mask 1 is used as a stepper reticle. In this embodiment, the light shielding layer 7 is formed in the non-transfer area other than the transfer area I.

As a result, when this halftone type phase shift mask 1 is used as a reticle of a stepper, a light passing region I'of the aperture of the stepper and a transfer region I of the halftone type phase shift mask 1 as a reticle are formed. Even if the exposure light radiates to the non-transfer region of the halftone type phase shift mask 1 with a slight gap between them, the exposure light radiated beyond this region is blocked by the light shielding layer 7 and is transmitted. Can not do it. As a result, it is possible to completely prevent unnecessary exposure light from reaching the non-transfer area on the transfer medium, and there is a slight deviation between the light passage area of the aperture and the transfer area of the halftone phase shift mask. In this case, it is possible to prevent the occurrence of exposure defects due to this shift.

The transparent substrate 2 is a quartz glass substrate whose main surface is mirror-polished (dimensions: length 6 inches × width 6 inches × thickness 0.
25 inches).

The low-transmittance layer 3 constituting the semi-translucent layer 5 is a Cr film having a film thickness of 21 nm and has a transmittance of 15% for exposure light having a wavelength of 365 nm. Further, the high transmittance layer 4 is
SOG (coated glass; spin-on
(Glass) film, and the phase of exposure light with a wavelength of 365 nm is 1
Shift by 80 °.

The light-shielding layer 7 is made of Cr and has a film thickness of 80.
nm film.

Next, the manufacturing process of the halftone type phase shift mask 1 having the above-mentioned structure will be described with reference to FIGS.

First, the low transmittance film 3a made of Cr is formed on the transparent substrate 2 by the sputtering method. next,
A coating liquid for forming a SiO2 coating film (Acuglass # 311 spin-on-glass (trade name) manufactured by Allied Signal Co., Ltd.) was dropped on the low transmittance film 3a, spread on the entire surface by a spin coating method, and then baked. The organic compound of the binder is volatilized to form the high-transmittance film 4a made of the SOG (spin-on-glass) film and the semi-transparent film 5a made of the low-transmittance film 3a and the high-transmittance film 4a. To do. Next, a Cr film having a thickness of 8 is formed on the high transmittance film 4a by a sputtering method.
The light-shielding film 7a is formed with a film thickness of 0 nm. Next, a positive electron beam resist (ZEP-810S: manufactured by Zeon Corporation) is applied on the light-shielding film 7a to a film thickness of 500 nm and baked to form a resist film 8a (see FIG. 3).

Next, the resist film 8a in the transfer region on the transparent substrate 2 is exposed to an electron beam having a desired pattern (see FIG. 4).

Next, the exposed resist film 8a is developed with a developing solution to form a resist pattern 8, and the resist pattern 8 is used as a mask to shield the light-shielding film 7.
a is etched with a predetermined etching solution to form a light-shielding film pattern 7b (see FIG. 5), and then the high transmittance film 4a is dry-etched (see FIG. 6). The dry etching of the high transmittance film 4a is performed under the following conditions using a reactive dry etching (RIE) parallel plate type dry etching apparatus.

Etching gas: mixed gas of CF ₄ and O ₂ Gas pressure: 0.1 Torr High frequency output: 200 W Next, after the resist pattern 8 is peeled off (see FIG. 7),
On the surface of the transparent substrate 2, a positive electron beam resist (ZEP-8
10S: manufactured by Nippon Zeon Co., Ltd.) to a film thickness of 500 nm and subjected to a baking treatment to form an electron beam resist film 9a (see FIG. 8), and then to form a light shielding layer 7 on this electron beam resist film 9a. Electron beam exposure (see FIG. 9).

Next, the electron beam resist film 9a is developed to form a resist pattern 9 in a region that does not contribute to the phase shift effect (see FIG. 10).

Thereafter, the resist pattern 9 is used as a mask to etch the exposed portions of the light-shielding film pattern 7b and the low transmittance film 3a with a predetermined etching solution to remove the exposed portions of these films (FIG. 11). Then, the remaining resist pattern 9 is removed to obtain the halftone phase shift mask 1 (see FIG. 1).

FIG. 12 is a diagram showing a comparison between the transfer characteristics of the halftone type phase shift mask 1 of Example 1 and the transfer characteristics of the conventional halftone type phase shift mask. In the graph of FIG. 12, the vertical axis is the light intensity on the transfer substrate, and the horizontal axis is the pattern dimension (unit: unit;
μm). Further, the solid line curve in the drawing is the example, and the alternate long and short dash line curve is the comparative example. These curves show the simulation of the light intensity when the pattern is transferred to the surface of the transferred substrate by the 1/5 reduction projection type stepper using each halftone type phase shift mask. The dimension W1 of the pattern (translucent part) of the halftone type phase shift mask is 2.5 μm.
m, the dimension W2 of the part that performs the phase shift function is 2.0μ
m. Also, the dimension W1 'on the transferred substrate is 0.5 μm.
m and W2 'are 0.4 .mu.m.

As can be seen from FIG. 12, when the halftone type phase shift mask of this embodiment is used, the light intensity becomes zero near the boundary between the light transmitting portion 6 and the semi light transmitting layer 5, and the contrast is high. In addition, in the region that does not contribute to the canceling action of the exposure light, the light intensity becomes zero and the leakage of the exposure light is completely prevented. Therefore, it is possible to obtain a resist pattern with a small film loss on the transferred substrate. Moreover, as is clear from FIG.
Than the light intensity is comparative example on the transfer substrate of the exposure light which has passed through the (W1) is larger the more the present embodiment, further, the light transmitting portion a region of the semi-light-transmitting portion and the semi-light-transmitting Area (W2) near the boundary with the part and contributing to the canceling action of exposure light
Since the light intensity of the exposure light passing through the substrate on the transfer target substrate is lower in the embodiment, the present embodiment is also advantageous in this respect also from the viewpoint of improving the contrast.

Further, in this embodiment, since the boundary portion between the transfer region and the transferred region on the phase shift mask is also covered with the light shielding layer, it is possible to prevent an unnecessary image from being formed on the transferred substrate. it can.

Further, the low transmittance layer 3 in this embodiment is 2
Since it is formed of a very thin film with a thickness of 1 nm, pinholes are likely to occur, but a light shielding layer 7 with a film thickness of 80 nm is formed above the pinhole.
Since most of the semi-translucent layer 5 is covered with,
Even if a pinhole is generated in the low transmittance layer 3, it is possible to prevent an unnecessary image from being formed when the pattern is transferred.

Further, in this embodiment, since the same material (Cr) is used for the low transmittance layer 3 and the light shielding layer 7, the light shielding layer 7 is used.
The second etching and the etching of the low transmittance layer 3 can be performed at the same time, and the process can be simplified.

In the present embodiment, the low-transmittance layer 3 may be made of chromium, in addition to chromium, containing chromium compounds such as chromium oxide, chromium nitride or chromium carbide, or molybdenum, tantalum or A material containing silicon in tungsten or a material containing nitrogen and / or oxygen may be used.

In addition to chromium, the light-shielding layer 7 may be a material containing silicon in molybdenum, a film of titanium, aluminum, tungsten, or the like. Also,
The low transmittance layer 3 and the light shielding layer 7 do not necessarily need to be the same material.

The light transmittance of the semi-translucent layer 5 is usually 1
It may be in the range of up to 50%, and practically 5 to 15% is often used.

(Second Embodiment) FIG. 13 shows a second embodiment of the present invention.
FIG. 14 is an end view of a cross section of the halftone phase shift mask according to Example 2, and FIGS. 14 to 20 are explanatory diagrams of the manufacturing process of the halftone phase shift mask according to Example 2. The second embodiment will be described below with reference to these drawings. In addition, since this embodiment is almost the same in the configuration except that the semi-translucent layer 5 in the above-described first embodiment is formed of a single-layer film, in the following description, the same functions as in the first embodiment will be described. The fulfilled portions are given the same reference numerals and a part of the description thereof is omitted.

In this embodiment, the semi-translucent layer 5 is a 180 nm thick oxynitride MoSi film having a wavelength of 365 nm.
The transmittance for the exposure light of 8 nm is 8%, and the phase of the exposure light is shifted by 180 °.

The light-shielding layer 7 is made of Cr and has a film thickness of 80 n.
The film of m is formed in a region that does not contribute to the phase shift effect.

The halftone type phase shift mask 1 having this structure can be manufactured as follows.

First, a single-layer semi-transparent film 5 for simultaneously controlling the transmittance and the phase difference made of MoSi oxynitride by a reactive sputtering method using Ar + O 2 + N 2 gas using a target of molybdenum silicide on the transparent substrate 1.
a is formed. Next, Cr is deposited to a film thickness of 80 nm on the semi-translucent film 5a by a sputtering method to form the light shielding film 7a. Then, a positive type electron beam resist (ZEP-810S: manufactured by Zeon Corporation) is formed on the light-shielding film 7a to a film thickness of 5
Then, the electron beam resist film 8a is formed by applying a coating of 00 nm and baking (see FIG. 14).

Next, the electron beam resist film 8 on the transparent substrate 1
An electron beam exposure of a desired pattern is applied to a (see FIG. 15).

Next, the exposed electron beam resist film 8a is formed.
Is developed and then baked to form a resist pattern 8,
Next, using the resist pattern 8 as a mask, the light-shielding film 7a is etched with a predetermined etching solution to form a light-shielding film pattern 7b (see FIG. 16).

Next, after etching the semi-transparent film 5a,
The resist pattern 8 is removed (see FIG. 17). The semi-transparent film 5a is etched under the following conditions using a reactive ion etching type parallel plate type dry etching apparatus.

Etching gas ... Mixed gas of CF4 and O2 Gas pressure ... 0.1 Torr High frequency output ... 200 W Next, a positive photoresist (AZ-135) was formed on the entire surface of the substrate.
0: manufactured by Sibley Co., Ltd.) is applied to a film thickness of 600 nm and baked to form a photoresist film 9a (see FIG. 18).

Next, the entire surface of the transparent substrate 1 is exposed from the back surface thereof and the light-shielding film pattern 7b is used as a mask (see FIG. 19). At this time, the irradiation amount is made larger than that in the case of obtaining a pattern having the same size as the light-shielding film pattern 7b so that the line width of the portion to be patterned becomes thick. Then, the photoresist 9a is developed, and the light-shielding film pattern 7b is etched with a predetermined etching solution using the resist pattern as a mask. At this time as well, it is important to make the etching time longer than that of the normal patterning when the exposure amount is increased. After that, the halftone type phase shift mask 1 of Example 2 can be obtained by removing the resist (see FIG. 13).

According to this embodiment, similarly to the first embodiment, it is possible to obtain a resist pattern having a high contrast and a small film loss, and also at the boundary between the transfer region and the non-transfer region on the phase shift mask. Since it is covered with the light-shielding layer, it is possible to prevent an unnecessary image from being formed on the transferred substrate.

Further, since the semi-translucent layer 5 is made of oxynitride MoSi and the light shielding layer 7 is made of chromium, both are not etched at the time of etching.

In this embodiment, MoSi oxynitride is used as the semi-translucent layer and chromium is used as the light-shielding layer. However, the semi-transmissive layer is not limited to this, and a single layer can provide a predetermined transmittance and phase difference. Any material that can be used as a semi-transparent film, such as a chromium oxide, a nitride, a fluoride, a carbide or a mixture thereof, a material in which a light absorbing material is mixed with silicon oxide, is used. be able to. However, when the method of this embodiment is used, it is necessary to select materials having resistance to the etching environments of the semitranslucent layer and the light shielding layer.

Further, in the above-mentioned embodiment, in the back exposure process, the irradiation amount of the back exposure is increased in order to form the light shielding film at a predetermined position. However, as shown in FIG. By arranging a reflecting substrate 11 on which a high-reflecting film 13 such as a chromium film is formed on the substrate 12 so as to be opposed to, the vicinity of the boundary with the light-transmitting portion on the semi-light-transmitting layer 5 is utilized by utilizing the reflecting action. May also be exposed.

Typical modifications of the present invention will be described below.

In the phase shift mask 1 shown in FIG. 21, the transparent substrate 2 is directly etched to form a part of the transparent substrate as a high transmittance layer 4, and the low transmittance layer 3 is formed on the high transmittance layer 4.
Is laminated, and the light shielding layer 7 is formed on a portion of the low transmittance layer 3 that does not contribute to the phase shift function.

The phase shift mask 1 shown in FIG. 22 has a light-shielding layer 7 provided at a predetermined position on a transparent substrate 2 and a single semi-translucent layer 5 formed at a predetermined position thereon. is there.
The semi-translucent layer 5 may have a two-layer structure of a high transmittance layer and a low transmittance layer.

In the present invention, the position where the light shielding layer is provided is preferably set so that W2 'on the transferred substrate is as small as possible in the range of 0.2 μm or more.
In other words, when using the 1/5 reduction projection type stepper,
It is preferable that W2 on the mask is as small as possible in the range of 1 μm or more. By making W2 as small as possible, it is possible to minimize the light leakage in the semi-transparent part, but when W2 is 1 μm or less, the canceling action near the boundary between the semi-transparent part and the translucent part is adversely affected. Because there is a possibility. However, since the dimension (W1) accuracy of the pattern is determined by the dimension accuracy of the semi-translucent portion, the dimension (W1) accuracy of the light shielding layer is not so required.

[0065]

As described above in detail, the halftone type phase shift mask according to the present invention cancels light at least in the mask pattern transfer region and near the boundary between the light transmitting portion and the semi-light transmitting portion. By providing the light-shielding layer in the semi-transparent portion that does not substantially contribute to the action, leakage of the exposure light in that portion can be suppressed. Therefore, the film loss of the resist can be reduced. In this case, the pattern accuracy of the mask pattern is determined by the pattern accuracy of the semi-transparent portion, and the pattern accuracy of the light-shielding layer and the thickness accuracy thereof are not so required, so that the design and formation thereof are relatively easy. Therefore, it is possible to almost completely prevent the leakage of exposure light, which is a drawback thereof, while utilizing the original advantages of the halftone type phase shift mask.

Further, the non-transfer area adjacent to the boundary between the mask pattern transfer area and the non-transfer area is used as a semi-transmissive part, and the semi-transmissive part of the non-transfer area is provided with a light-shielding part having a predetermined width or more. Due to the provision, when this halftone type phase shift mask is used as a reticle of a stepper, there is a slight deviation between the light passing area of the stepper aperture and the transfer area of the halftone type phase shift mask which is a reticle. Therefore, even if the exposure light is projected to the semi-transparent portion in the non-transfer area of the phase shift mask and is irradiated, the exposure light projected and irradiated is blocked by the light shielding portion and cannot be transmitted. This allows
It is possible to completely prevent unnecessary exposure light from reaching the non-transferred area on the transferred material, and when there is some deviation between the light passing area of the aperture and the transfer area of the halftone type phase shift mask. Also, it is possible to prevent the occurrence of exposure defects due to this deviation.

Further, according to the halftone type phase shift mask blank of the present invention, the halftone type phase shift mask blank which can easily manufacture the halftone type phase shift mask of the present invention can be obtained.

[Brief description of drawings]

FIG. 1 is a view showing a configuration of a halftone type phase shift mask according to a first embodiment of the present invention, which is an end view of a cross section taken along line I-I of FIG.

FIG. 2 is a plan view of the halftone phase shift mask according to the first embodiment.

FIG. 3 is an explanatory diagram of a manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 4 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 5 is an explanatory view of the manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 6 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 7 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 8 is an explanatory diagram of a manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 9 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 10 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 11 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 12 is a diagram showing a comparison between the transfer characteristics of the halftone phase shift mask 1 of Example 1 and the transfer characteristics of a conventional halftone phase shift mask.

FIG. 13 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 14 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 15 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 16 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 17 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 18 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 19 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 20 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 21 is a diagram showing a modified example of the present invention.

FIG. 22 is a diagram showing a modified example of the present invention.

FIG. 23 is an explanatory diagram of a conventional example of the present invention.

FIG. 24 is an explanatory diagram of a conventional example of the present invention.

FIG. 25 is an explanatory diagram of a conventional example of the present invention.

FIG. 26 is an explanatory diagram of a conventional example of the present invention.

FIG. 27 is an explanatory diagram of a conventional example of the present invention.

FIG. 28 is an explanatory diagram of a conventional example of the present invention.

[Explanation of symbols]

1 ... Halftone type phase shift mask, 2 ... Transparent substrate,
3 ... Low transmittance layer, 4 ... High transmittance layer, 5 ... Semi-transmissive layer, 6 ...
Translucent part, 7 ... Light-shielding layer. ．

Claims (3)

(57) [Claims] 1. A mask for transferring a fine pattern, comprising:
The mask pattern formed in the transfer region on the transparent substrate has a light-transmitting portion that transmits light of intensity that substantially contributes to exposure and a semi-light-transmitting portion that transmits light of intensity that does not substantially contribute to exposure. Then, by shifting the phase of the light passing through the semi-transparent portion to make the phase of the light passing through the semi-transparent portion different from the phase of the light passing through the transparent portion, In the halftone phase shift mask capable of maintaining good contrast at the boundary by utilizing the canceling effect of the light passing through the vicinity of the boundary between the semi-light -transmitting portion and the light-transmitting portion, 10% or more, shielded above or below the semi-transparent portion that does not substantially contribute to the canceling action of light in the vicinity of the boundary between the translucent portion and the semi-transparent portion within the mask pattern transfer region. a layer, the mask pattern transfer region and the non-transfer area Next to the boundary
The non-transfer area that touches is the semi-transparent area, and this non-transfer area
A semi-translucent part of the area is provided with a light-shielding layer having a width larger than a predetermined value.
Halftone type phase shift mask characterized by and . 2. A mask for transferring a fine pattern, comprising:
The mask pattern formed in the transfer region on the transparent substrate has a light-transmitting portion that transmits light of intensity that substantially contributes to exposure and a semi-light-transmitting portion that transmits light of intensity that does not substantially contribute to exposure. Then, by shifting the phase of the light passing through the semi-transparent portion to make the phase of the light passing through the semi-transparent portion different from the phase of the light passing through the transparent portion, In the halftone phase shift mask capable of maintaining good contrast at the boundary by utilizing the canceling effect of the light passing through the vicinity of the boundary between the semi-light -transmitting portion and the light-transmitting portion, 10% or more, above or below the semi-transparent portion in the mask pattern transfer area
A light-shielding layer is provided, and is adjacent to the boundary between the mask pattern transfer area and the non-transfer area.
The non-transfer area that touches is the semi-transparent area, and this non-transfer area
A light-shielding layer having a predetermined width or more is provided in the semi- light -transmitting portion of the area, and the light-shielding layer in the transfer region of the mask pattern is in the area of the semi- light -transmitting portion and includes the light -transmitting portion and the semi- light -transmitting portion. It is provided in a region including a region near the boundary between the and A halftone type phase shift mask characterized in that 3. A pattern transfer method, wherein a pattern is transferred to a transfer substrate by using the halftone type phase shift mask according to claim 1 .