JP2000286182A - Manufacture of phase shift mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the time required to complete a process of manufacturing Levenson-type phase shift masks. SOLUTION: A Levenson-type phase shift mask, having different phase difference, is manufactured. A resist 32 is applied to a quartz board 23. The resist 32 is exposed, in such a manner that the thickness of a resist film after development corresponds to an etched depth which should be achieved in the board 23. The resist 32 and the board 23 which remain after the development are etched in batch. The remaining resist 32 is removed, to thereby obtain a mask board having different etched depths.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a phase shift mask, and more particularly, to a method for manufacturing a phase shift mask used in a fine processing technique in a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art In recent years, semiconductor devices have been steadily miniaturized, and a pattern forming technology of 0.15 μm or less has become necessary. ing. On the other hand, with the advancement of functions of system LSIs, a technique for forming a high-speed and high-performance logic unit is required.

To process a high-performance logic section,
In photolithography, an exposure technique that can form a fine isolated pattern with high accuracy is required. As a technique for forming a fine isolated pattern, for example, a pattern forming method using a Levenson-type phase shift mask proposed by HYLiu et al. Is known (Proc. SPIE, V
ol. 3334, p. 2 (1998)). A pattern forming method using a Levenson-type phase shift mask is a method of forming a fine pattern by imparting a phase difference of 0 ° and 180 ° to transmitted light by a mask to enhance light coherence.

FIG. 6 is a view for explaining a pattern forming method using a Levenson type phase shift mask (hereinafter, referred to as a “Levenson mask”). More specifically, FIG. 6A shows an ideal resist pattern 10 formed on a wafer, and FIGS. 6B and 6C show
The structures of the Levenson masks 11 and 12 are respectively shown. Hereinafter, a case where a positive type resist is formed in the pattern 10 shown in FIG. 6A will be described with reference to FIG.

The Levenson mask 11 shown in FIG.
Is a light shielding pattern 14 composed of a chromium (Cr) film.
And a region that transmits light without a phase shift (hereinafter, referred to as
A region that gives a 180 ° phase shift to transmitted light (hereinafter, referred to as a “phase 180 ° region 1”).
8 "). When the positive type resist is exposed using the Levenson mask 11 having such a structure, the light intensity on the wafer at the position of the light shielding pattern 14 is sufficiently weakened. Therefore, according to the Levenson mask 11, the resist pattern 10 can be formed in substantially the same pattern as the light-shielding pattern 14.

[0006]

However, when the Levenson mask 11 shown in FIG. 6B is used, the light intensity on the wafer is not limited to the area covered by the light-shielding pattern 14 but to the phase 0 ° area 16. And at the boundary of the 180 ° phase region. For this reason, according to the Levenson mask 11, a resist pattern remains on those boundaries.

Therefore, when performing exposure using the Levenson mask 11 shown in FIG. 6B, it is necessary to perform double exposure using another mask in order to remove an extra resist pattern. become. Such double exposure requires extremely high alignment accuracy in the second exposure, or the lithography process becomes longer,
There are problems such as a decrease in device production efficiency.

Another method for forming the resist pattern 10 shown in FIG. 6A is to use a Levenson mask 12 shown in FIG. 6C. Levenson mask 1
2 is a phase 0 ° region 16 where the phase shift amount is 0 °;
A region for generating a phase shift amount of 90 ° or 270 ° (hereinafter, referred to as “second phase region 20”) is provided near a boundary with a phase 180 ° region where the phase shift amount is 180 °.

According to such a Levenson mask 12, sufficient intensity can be given to transmitted light on the wafer near the boundary between the phase 0 ° region and the phase 180 ° region. Therefore, according to the Levenson mask 12, it is possible to prevent an extra resist pattern from remaining at the boundary.

However, in order to manufacture the Levenson mask 12 shown in FIG.
A second phase region 20 for generating a phase shift amount of 180 ° is created, and then a phase 18 for generating a phase shift amount of 180 ° is generated.
A complicated mask manufacturing process such as creating a 0 ° region is required. For this reason, when the Levenson mask 12 is used, there are problems such as a prolonged mask manufacturing process and an increase in device cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is intended to provide a phase shift mask capable of manufacturing a Levenson-type phase shift mask capable of forming an isolated pattern with high accuracy in a short period of time. An object of the present invention is to provide a method for manufacturing a mask.

[0012]

According to a first aspect of the present invention, there is provided a method of manufacturing a phase shift mask for producing a phase difference in transmitted light, comprising the steps of: providing a resist on a mask substrate; Forming a resist film having a different remaining film thickness on the different portion by applying light or an electron beam to the different portion on the resist with a different exposure amount, and developing the resist. And forming a plurality of portions having different engraving amounts on the mask substrate by etching the resist film and the mask substrate collectively,
It is characterized by having.

According to a second aspect of the present invention, there is provided the phase shift mask manufacturing method according to the first aspect, wherein the engraving amounts given to the plurality of portions of the mask substrate are generated in the respective portions. Corresponding to the amount of phase shift to be performed, the difference in the remaining film thickness of the resist film in each of the different portions corresponds to the difference in the amount of engraving to be formed in those portions, and the amount of exposure Is set such that the difference occurs in the remaining film thickness of the different portion of the resist film.

According to a third aspect of the present invention, there is provided a method of manufacturing a phase shift mask according to the first or second aspect, wherein a portion of the mask substrate on which the largest engraving amount is to be formed is formed of the resist. The remaining film thickness is zero.

According to a fourth aspect of the present invention, there is provided the method for manufacturing a phase shift mask according to any one of the first to third aspects, wherein the amount of exposure is the amount of light applied to the resist. It is characterized by being adjusted by the intensity of the electron beam.

Further, according to a fifth aspect of the present invention, there is provided the method for manufacturing a phase shift mask according to any one of the first to third aspects, wherein the amount of exposure is the amount of light or It is characterized by being adjusted by the electron beam irradiation pattern.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals, and redundant description will be omitted.

Embodiment 1 FIG. 1 is a plan view of a Levenson-type phase shift mask (Levenson mask) 22 manufactured by the manufacturing method according to the first embodiment of the present invention. The Levenson mask 22 of the present embodiment is provided with a quartz substrate 23 as a base material, and includes a light-shielding pattern 24, a phase 0 ° region 26, a phase 90 region 28, and a phase 180 ° region 3.
0 is provided.

The light-shielding pattern 24 is a pattern for blocking light transmission, and is formed of a chromium (Cr) film formed on a quartz substrate 23. The phase 0 ° region 26, the phase 90 region 28, and the phase 180 ° region 30 are regions that transmit light of a predetermined frequency while generating a predetermined amount of phase shift. Specifically, the phase 90 region 28 is 90 ° with respect to light transmitted through the phase 0 ° region 26.
Is a region where a phase shift amount of 180 ° is generated.
The region 30 is 1 to light transmitted through the phase 0 ° region 26.
This is an area where a phase shift amount of 80 ° is generated.

Each of the phase 90 region 28 and the phase 180 ° region 30 is realized by providing a predetermined step on the quartz substrate 23. When the wavelength of the light applied to the Levenson mask 22 is, for example, 193 nm, the engraved amount of the step in the quartz substrate 23 is:
The phase shift amount is 86 nm in the phase 90 region 28 where the phase shift amount of 90 ° is generated, and 172 nm in the phase 180 ° region 30 where the phase shift amount of 180 ° is generated.

In the process of forming the Levenson mask 22, a light-shielding pattern 24 is first formed on a quartz substrate 23 using chrome. Next, the quartz substrate 23 is carved,
Steps for forming the phase 90 region 28 and the phase 180 ° region 30 are provided.

FIG. 2 is a schematic diagram for explaining a process of forming a step on the quartz substrate 23. In addition, FIG.
FIG. 2D shows the Levenson mask 22 shown in FIG.
II shows a cross section obtained by cutting along a straight line. In the step forming process, the part A shown in FIG. 2A finally has the phase 180 ° region 30 (the engraving amount 172n).
2 (a), the portion B shown in FIG. 2 (a) is in the phase 90 region 28 (the engraving amount is 86 nm).

In the step forming process, specifically, a resist 32 is first applied on the quartz substrate 23. Next, the portions A and B of the resist 32 are exposed at predetermined exposure amounts by photolithography (FIG. 2).
(A)).

A development process for dissolving and removing the exposed portion of the resist 32 is performed. In the present embodiment, the above-described exposure and development are performed by the resist 3
2 is completely dissolved, and the B portion is incompletely dissolved so as to have a predetermined resist residual film (FIG. 2B).

Next, the resist 32 remaining after the development
By simultaneously etching the pattern and the underlying quartz substrate 23, a predetermined engraving is provided on the quartz substrate 23 (FIG. 2 (c)).

Finally, by removing the resist 32 on the quartz substrate 23, the phase 1 is applied to the A region and the B region, respectively.
The Levenson mask 22 having the engraving required for the 80 ° region 30 or the phase 90 region 28 is formed (FIG. 2D).

The following is a positive type electron beam resist manufactured by Tokyo Ohka.
A case where the above-described step forming process is performed using the EBR 1000 as the resist 32 will be described. It is known that the etching rate when quartz is etched with C ₂ F ₆ is 20.7 nm / min (A. Tamura et al. SPIE, 2254, 228 (1
994)). Therefore, when the quartz substrate 23 is etched with C ₂ F ₆ , the etching time for forming a predetermined engraving (172 nm) in the portion A is 8.3 min. In the manufacturing method of the present embodiment, this time 8.3 min is the total etching time in the step forming process.

In this embodiment, the portion B of the quartz substrate 23 is continuously etched after the portion B of the resist 32 is removed. The etching time for forming the predetermined engraving (86 nm) in the portion B of the quartz substrate 23 is 4.15 min. Therefore, the resist 32 in the B portion
The etching time for removing the quartz is from the total etching time 8.13 min to the etching time 4.1 seconds for the quartz substrate 23.
It becomes 4.15 min after subtracting 5 min.

The etching rate when etching the resist material OEBR1000 with C ₂ F ₆ is 22.0 nm / min (AT
amura et al. SPIE, 2254, 228 (1994)). Therefore, the remaining film to be given to the resist 32 in the portion B is 91.3n.
m.

FIG. 3 shows the relationship between the resist film thickness after development of the resist material OEBR1000 and the amount of exposure. As shown in FIG. 3, the film thickness of the resist material OEBR1000 after development shows exposure dose dependency. Note that the relationship shown in FIG.
With an initial film thickness of 0.5 μm and a developing time of 5 min.
It is the result when it is set as.

According to the relationship shown in FIG. 3, the exposure dose to the portion B where a 91.3 nm resist remaining film is to be ensured is 45 μC / cm ^2.
In addition, it can be seen that the exposure amount of 50 μC / cm ² or more is required for the portion A where the resist 32 should be completely dissolved.

In the manufacturing method of this embodiment, the exposure of the resist 32 is performed under the above-described exposure conditions. That is, an initial film thickness of 0.5 μm is given to the resist 32,
The exposure amount of the portion A becomes 50 μC / cm ² or more, and
The resist 32 is irradiated with light or an electron beam so that the exposure amount of the portion B becomes 45 μC / cm ² . Therefore, according to the manufacturing method of the present embodiment, the phase 90 region 28 for generating the phase shift amount of 90 ° and the phase 180 for generating the phase shift amount of 180 ° are obtained by performing the exposure and etching processes only once. ° region 30 can be provided in quartz substrate 23 at the same time.

In the above embodiment, the resist material constituting the resist 32 is limited to the positive type electron beam resist EBR1000 manufactured by Tokyo Ohka, but the present invention is not limited to this. 32 may be made of another resist material.

The above-described exposure conditions and etching conditions are examples of conditions for forming the phase 90 region 28 and the phase 180 ° region 30 in one exposure and etching process. The conditions are not limited. That is, the exposure condition and the etching condition in the step forming process are appropriately set according to the etching rate of the substrate and the resist material, the photosensitive characteristics of the resist material, and the like so that a desired step can be formed by one exposure and etching process. I just need.

In the above embodiment, the phase 0
Although the phase 90 region 28 is formed between the ° region 26 and the phase 180 ° region 30, the present invention is not limited to this, and the phase shift amount of 270 ° is set between them. The generated phase 270 region may be formed.

In the above embodiment, the resist 32 is formed using a positive resist material. However, the present invention is not limited to this, and the resist 32 may be formed of a negative resist material. May be configured.

Further, in the above embodiment, the quartz substrate 23 is used as the base material of the Levenson mask 22, but the present invention is not limited to this, and the base material of the Levenson mask 22 may be other than quartz. (For example, calcium fluoride) may be used.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 shows exposure data 34 used in the mask manufacturing method of the present embodiment. The exposure data 34 shown in FIG. 4 is used in the present embodiment to manufacture the Levenson mask 22 shown in FIG.

In this embodiment, the Levenson mask 2
2, the phase 90 region 28 and the phase 180 ° region 30
As in the case of the first embodiment, (1) a resist 32 is formed on a quartz substrate 23 (see FIG. 2A), and (2) portions A and B are exposed at different exposure doses (50 μC / cm ^2). And 45μC
/ cm ² ) (FIG. 2 (b)), and further, (3) by etching the portions A and B simultaneously after development (FIG. 2).
(C), FIG. 2 (d)) are formed simultaneously.

In the course of the above series of processing, the resist 3
The exposure process 2 is performed using a drawing apparatus. The drawing apparatus used in the present embodiment can irradiate an arbitrary coordinate position with an electron beam having a light amount corresponding to data given in advance.

In the manufacturing method of the present embodiment, the exposure data 34 shown in FIG. In FIG. 4, a region 36 denoted by reference numeral C and a region 38 denoted by reference numeral D respectively have a phase of 180 ° shown in FIG.
It corresponds to the region 30 and the phase 90 region 28. In the exposure data 34, the exposure amount of the C region 36 is 50 μC
/ cm ² , and the exposure amount of the D region 38 is 45 μC / cm ² ,
Each is set.

According to the supply of the exposure data 34, the drawing apparatus operates the resist 32 in the portion A (FIG. 2).
(Refer to (a)), an exposure amount of 50 μC / cm ^{2 is applied, and} an exposure amount of 45 μC / cm ² is applied to the portion B of the resist 32. Therefore, according to the manufacturing method of the present embodiment, the resist 32 is completely removed from the portion A when the development is completed, and
A resist having a desired film thickness can be left in the portion. Therefore, according to the manufacturing method of the present embodiment, the Levenson mask 22 shown in FIG. 1 can be manufactured with high accuracy.

In the above embodiment, the exposure data 34 supplied to the drawing apparatus is an example of data for manufacturing the Levenson mask 22 shown in FIG.
Data supplied to the drawing apparatus is not limited to this. That is, exposure data according to the pattern of the Levenson mask to be manufactured or the like may be supplied to the drawing apparatus.

Embodiment 3 FIG. Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 5 shows exposure data 40 used in the mask manufacturing method of the present embodiment. The exposure data 40 shown in FIG. 5 is used in the present embodiment to manufacture the Levenson mask 22 shown in FIG.

In this embodiment, the Levenson mask 2
In the manufacturing process of No. 2, exposure processing of the resist 32 using the drawing apparatus is performed as in the case of the second embodiment. The drawing apparatus used in the present embodiment can irradiate a beam with a predetermined light amount to an arbitrary coordinate position.

In the manufacturing method of the present embodiment, the exposure data 40 shown in FIG. In FIG. 5, a region 42 denoted by reference numeral E and a region 44 denoted by reference numeral F respectively have a phase of 180 ° shown in FIG.
It corresponds to the region 30 and the phase 90 region 28.

In FIG. 5, a hole-shaped pattern is set in the F region 44 as a beam irradiation pattern. On the other hand, a large rectangular pattern is set in the area E as a beam irradiation pattern. In a fine pattern such as a hole, a substantial exposure amount on a mask at the time of exposure is smaller than an exposure amount of a pattern having a large area. Therefore, the exposure amount on the mask can be arbitrarily set by adjusting the size and density of the hole pattern.

In this embodiment, the exposure data 40
The exposure intensity in the E region 42 and the exposure intensity in the F region 44 are set to be the same, and the two regions are set so that an appropriate exposure amount can be given to each of the two regions. More specifically, the exposure data 40 indicates that the substantial exposure amount of the E region 42 is 50 μC / cm ² while the exposure intensity in the E region 42 and the exposure intensity in the F region 44 are the same. 44 is set so that the substantial exposure amount is 45 μC / cm ² . Therefore, according to the manufacturing method of the present embodiment, the Levenson mask 22 shown in FIG. 1 can be manufactured with high accuracy, as in the case of the second embodiment, without changing the exposure intensity for each region.

[0049]

Since the present invention is configured as described above, it has the following effects. Claim 1
According to the invention described above, after a resist film having a different remaining film thickness is formed in a different portion, the resist film and the mask substrate can be collectively etched. The mask substrate is etched for a longer time as the remaining thickness of the resist film is smaller. For this reason, the mask substrate
A difference in engraving amount occurs according to the difference in the remaining film thickness of the resist film. Light transmitted through the mask substrate has a different phase shift amount depending on the difference in the engraving amount. Therefore, according to the manufacturing method of the present embodiment, a plurality of regions that generate different amounts of phase shift can be easily formed by performing only one exposure / etching process.

According to the second aspect of the present invention, the difference in the engraving amount of the mask substrate is set in accordance with the difference in the amount of phase shift to be generated, and the resist is formed in correspondence with the difference in the engraving amount. The difference of the remaining film thickness is set. Further, the exposure conditions of the resist are set so that the difference in the remaining film thickness occurs. Therefore, according to the present invention, a phase shift mask that generates a desired phase difference can be manufactured by performing only one exposure / etching process.

According to the third aspect of the present invention, the resist is completely removed from the portion requiring the largest engraving amount before the etching. Therefore, according to the present invention, the etching of the mask substrate is efficiently performed,
A phase shift mask can be manufactured efficiently.

According to the fourth aspect of the invention, by adjusting the irradiation intensity of the light or the electron beam to the resist, a desired exposure amount can be accurately given to each part of the resist. Therefore, according to the present invention, a phase shift mask having desired characteristics can be easily and accurately manufactured.

According to the fifth aspect of the present invention, a desired exposure amount can be given to each part of the resist with high accuracy by adjusting the pattern of light or electron beam irradiation on the resist. Therefore, according to the present invention, a phase shift mask having desired characteristics can be easily and accurately manufactured.

[Brief description of the drawings]

FIG. 1 is a plan view of a Levenson-type phase shift mask manufactured by a manufacturing method according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining each step of the manufacturing method according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a residual film after development of a resist material used in the first embodiment of the present invention and an exposure amount.

FIG. 4 is a diagram showing exposure data used in a second embodiment of the present invention.

FIG. 5 is a diagram showing exposure data used in a third embodiment of the present invention.

FIG. 6A is a plan view showing an ideal resist pattern to be formed using a mask. FIG. 6B is a plan view of a first example of the Levenson-type phase shift mask. FIG. 6C shows a second example of the Levenson-type phase shift mask.
FIG. 6 is a plan view of the example of FIG.

[Explanation of symbols]

 Reference Signs List 22 Levenson type phase shift mask 23 Quartz substrate 24 Light shielding pattern 26 Phase 0 ° region 28 Phase 90 ° region 30 Phase 180 ° region 32 Resist 34; 40 Exposure data

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Junji Miyazaki 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Semiconductor Advanced Technologies (72) Inventor Toshio Onodera 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor: Masaya Uematsu, Inventor Masaya Uematsu 292, Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture Intra-technology by Semiconductor (72) Inventor: Toru Ogawa 292, Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture BB03 BB10 BB14 BB18 BC05 BC09 BC24 BC27

Claims (5)

[Claims] 1. A method for manufacturing a phase shift mask for producing a phase difference in transmitted light, comprising: applying a resist on a mask substrate; and applying different amounts of light or electrons to different portions on the resist. Irradiating a beam; developing the resist to form a resist film having a different remaining film thickness in the different portion; and etching the resist film and the mask substrate all at once, Forming a plurality of portions having different engraving amounts on the mask substrate. A method for manufacturing a phase shift mask, comprising: 2. An engraving amount applied to the plurality of portions of the mask substrate corresponds to a phase shift amount to be generated in each portion, and a remaining film thickness of the resist film in each of the different portions. Corresponds to the difference in the engraving amount to be formed in those portions, and the exposure amount is set such that the difference occurs in the remaining film thickness of the different portions of the resist film. The method for manufacturing a phase shift mask according to claim 1, wherein 3. The method of manufacturing a phase shift mask according to claim 1, wherein the remaining film thickness of the resist is zero in a portion where the largest engraving amount is to be formed in the mask substrate. . 4. The manufacturing method according to claim 1, wherein the exposure amount is adjusted by the intensity of light or an electron beam irradiated to the resist. Method. 5. The phase shift mask according to claim 1, wherein the exposure amount is adjusted by an irradiation pattern of light or an electron beam applied to the resist. Production method.