JP2002365782A - Method of manufacturing phase shift mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently manufacture a phase shift mask with a smaller number of process steps. SOLUTION: This method comprises using a high-sensitivity negative type resist 14 and a low-sensitivity type negative resist 15 and exposing the high- sensitivity negative type resist 14a and the low-sensitivity type negative resist 15a in a light shielding band region 10a and exposing the high-sensitivity negative type resist 14b in a halftone region 10b. As a result, the resist film thickness of the halftone region 10b after development is made thinner than the resist film thickness of the light shielding band region 10a. The high-sensitivity negative type resist 10b of the halftone region 10b is simultaneously removed to expose a light shielding film 13 by dry etching of an opening region 10c. In the light shielding band region 10a, the resist remain and the light shielding film 13 is protected. Accordingly, the light shielding film 13 of the halftone region 10b is removed by wet etching and the light shielding film 13 of the light shielding band region 10a is made to remain. As a result, the phase shift mask can be manufactured by one time of drawing and the process steps can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a phase shift mask, and more particularly, to a light-shielding band for blocking light, a halftone portion for transmitting a part of light and inverting the phase of the light, and transferring the light onto a wafer. The present invention relates to a method for manufacturing a phase shift mask in which an opening serving as a pattern is formed on a substrate by electron beam lithography.

[0002]

2. Description of the Related Art In a lithography process for manufacturing a semiconductor device, a processing limit of a formed pattern depends on an exposure wavelength. In recent years, the structure of semiconductor devices has become increasingly finer, and the development of fine pattern formation technology has been promoted. One of such techniques is an exposure technique using a phase shift mask.

The phase shift mask is provided on a part of the mask with a phase shifter that inverts the phase of incident light and transmits the light. For example, in the case where a phase shifter and a portion other than the phase shifter, that is, an opening serving as a pattern to be transferred onto a wafer are phase shift masks formed adjacent to each other, light passing through the phase shifter and the opening are used. The transmitted light interferes when transferred onto the wafer. At this time, the light intensity distribution on the wafer is different from the light intensity distribution of the light passing through the phase shifter and the light intensity distribution of the light passing through the opening because the light phase is shifted. Cancel each other out. As a result, the resolution at this boundary portion is improved and the pattern becomes clear. When such a phase shift mask is not used, the light intensity distribution on the wafer between adjacent patterns has the same light phase, so that the skirts are strengthened by overlapping, and the resolution at the boundary portion is reduced. Therefore, by using a phase shift mask, it is possible to cope with the formation of a fine pattern.

As such a phase shift mask, various mask structures such as a Levenson type, a chromeless type, and a halftone type have been proposed. The Levenson-type or chromeless-type phase shift mask is a method having a high resolution improving effect, but it may be difficult to apply depending on the pattern. To avoid this problem, the pattern arrangement may be changed, but the degree of freedom in pattern design is reduced and the burden on the design is increased. Also, there is a problem that the mask itself is difficult to manufacture.

On the other hand, in a halftone type phase shift mask, a halftone film having a transmittance of about several percent and partially transmitting light even in a light shielding portion is used as a phase shifter. Therefore, the phase of the light that has passed through the halftone film and the phase of the light that has passed through the opening are inverted, and the resolution of the transfer pattern is improved. This resolution improving effect is smaller than that of the Levenson type or the chromeless type. However, since masks can be manufactured relatively easily, practical application to various patterns is being studied.

[0006]

SUMMARY OF THE INVENTION The half-tone phase shift mask (HT)
In the case of PSM), light is slightly transmitted from the halftone film. Therefore, when the outer frame that separates the exposure area where the pattern is formed on the mask from the other area is made of the halftone film, The frame is partially exposed and becomes unclear. Therefore, in the HTPSM, it is necessary to provide a light-shielding band made of chrome or the like on the outer frame.

FIG. 6 shows a conventional method of manufacturing an HTPSM.
13 will be described in order with reference to FIG. FIG. 6 is a schematic sectional view of the HTPSM in a conventional first drawing step.

On a quartz glass substrate 101, a halftone film 102 slightly transmitting light and a light shielding film 103 made of chromium and shielding light are formed sequentially. Next, a first negative resist film 104 for forming a mask pattern is applied on the light-shielding film 103 and prebaked. The first negative resist film 104 is exposed to an electron beam to draw a mask pattern, thereby forming an unexposed portion 104a and an exposed portion 104b of the first negative resist film 104.

FIG. 7 shows a conventional HTP in the first developing step.
It is an outline sectional view of SM. After the first drawing step, development is performed to remove the unexposed portions 104a of the first negative resist film 104 shown in FIG. 6 and form a mask pattern by the exposed portions 104b.

FIG. 8 is a schematic sectional view of the HTPSM in a conventional first etching step. After the first development step, dry etching is performed to remove the halftone film 102 and the light-shielding film 103 in a region of the first negative resist film 104 that is not masked by the exposed portion 104b.

FIG. 9 shows a conventional HTP in a first cleaning step.
It is an outline sectional view of SM. After the first etching step, the exposed portion 104 of the first negative resist film 104 shown in FIG.
After b is peeled off and washed, a foreign substance inspection is performed.

FIG. 10 shows a conventional HT in the second drawing step.
FIG. 2 is a schematic sectional view of a PSM. After the first cleaning step, a second negative resist film 105 is formed on the entire surface of the substrate. And
On top of this, a conductive film 106 is further formed for the purpose of preventing displacement due to charging during electron beam processing. This conductive film 1
The second negative resist film 105 is irradiated with an electron beam from above to draw a mask pattern, and the unexposed portion 105a and the exposed portion 105b of the second negative resist film 105 are drawn.
To form

FIG. 11 shows a conventional HT in the second developing step.
FIG. 2 is a schematic sectional view of a PSM. After the second drawing step, FIG.
After the conductive film 106 shown in FIG.
0, the unexposed portion 10 of the second negative resist film 105
5a is removed. Thereby, a part of the light shielding film 103 is exposed.

FIG. 12 is a schematic sectional view of the HTPSM in the second conventional etching step. After the second development step,
The halftone portion 100b is formed by performing wet etching to remove the exposed light shielding film 103 shown in FIG.

FIG. 13 shows a conventional HT in the second cleaning step.
FIG. 2 is a schematic sectional view of a PSM. After the second etching step,
Exposure part 1 of second negative resist film 105 shown in FIG.
05b is peeled off and washed. Thereby, the light-shielding band 100
a, an opening 100c is formed. Further, a foreign substance inspection is performed, and the HTPSM 100 is manufactured.

As described above, in the HTPSM 100, an electron beam is formed on the quartz glass substrate 101 in order to form the light-shielding band 100a for dividing the exposure region and the halftone portion 100b formed between the adjacent openings 100c. Must be performed twice. Further, following each drawing step, development, etching, and cleaning steps are required, and the number of manufacturing steps is large, and the manufacturing takes time.
In addition, there is a problem that foreign substances are easily attached and defects are generated due to the large number of manufacturing steps.

The present invention has been made in view of such a point, and an object of the present invention is to provide a method of manufacturing a phase shift mask that can be manufactured efficiently by reducing the number of steps.

[0018]

According to the present invention, there is provided a method of manufacturing a phase shift mask having a light-shielding band, a halftone portion, and an opening, wherein a halftone film, a light-shielding film and a high-sensitivity negative film are formed on a substrate. A resist and a low-sensitivity negative resist are sequentially formed, and a high-sensitivity negative resist and a low-sensitivity negative resist in a light-shielding band region, which is a region to be a light-shielding band, and a halftone region, which is a region to be a halftone portion, are formed. After exposing the high-sensitivity negative resist with a predetermined exposure amount and developing, respectively, the light-shielding film and the halftone film in the opening area which is an area to be an opening by dry etching, and the high-sensitivity negative resist in the halftone area And removing the light-shielding film in the halftone region by wet etching.

According to the above configuration, the light-shielding band region, which is a region to be a light-shielding band of the phase shift mask, and the halftone region, which is a region to be a half-tone portion of the phase shift mask, are respectively exposed at predetermined exposure amounts. By doing so, a high-sensitivity negative resist and a low-sensitivity negative resist remain in the light-shielding band region after development, and only the high-sensitivity negative resist remains in the halftone region. As a result, the resist film thickness in the halftone region becomes smaller than the resist film thickness in the light-shielding band region. In dry etching performed using this as a mask, together with the light-shielding film and the halftone film in the opening region that is the region to be the opening of the phase shift mask, the high-sensitivity negative resist left in the halftone region is also etched. The light-shielding film in the halftone region is exposed. On the other hand, since the resist film thickness in the light-shielding band region is larger than that in the halftone region, the light-shielding film in this region is protected by the resist even after the etching.
When wet etching is performed in this state, only the exposed light-shielding film in the halftone region is etched and removed, and a phase shift mask in which a light-shielding portion, a halftone portion, and an opening are formed on a substrate is manufactured. .

[0020]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 are explanatory diagrams of the method of manufacturing the HTPSM.

FIG. 1 is a schematic sectional view of the HTPSM in a writing step. On a quartz glass substrate 11, a halftone film 12 slightly transmitting light and a light shielding film 13 made of chromium and shielding light are sequentially formed. Next, a high-sensitivity negative resist 14 is applied on the light-shielding film 13 and pre-baked. Further, the high-sensitivity negative resist 14
A low-sensitivity negative-type resist 15 is applied thereon and prebaked.

In drawing, both the low-sensitivity negative resist 15a formed in the light-shielding band region 10a, which is the light-shielding band of the phase shift mask, and the high-sensitivity negative resist 14a formed in the lower layer are exposed. The amount of exposure of the electron beam is adjusted in such a manner. The halftone region 10b, which is a region to be a halftone portion of the phase shift mask, is drawn by using the high-sensitivity negative resist 14 formed in this region.
The exposure amount of the electron beam is adjusted so that only b is exposed.
Further, the opening region 10c, which is the region to be the opening of the phase shift mask, is not irradiated with the electron beam and is not exposed. After the drawing is completed, the process proceeds to the next developing step.

FIG. 2 is a schematic sectional view of the HTPSM in the developing step. By performing development after drawing, the exposed high-sensitivity negative resist 14a and the exposed low-sensitivity negative resist 15a remain on the light-shielding film 13a in the light-shielding band region 10a. Also, the halftone region 10b
Only the exposed high-sensitivity negative resist 14b remains on the light-shielding film 13b. That is, the halftone region 10
The resist film thickness b is formed to be thinner than the resist film thickness of the light-shielding band region 10a by the thickness of the low-sensitivity negative resist 15 substantially. In the opening region 10c, since the electron beam is not irradiated, the resist is entirely removed.

FIG. 3 shows the HTP in the first etching step.
It is an outline sectional view of SM. After the development, dry etching is performed using the formed resist as a mask. Thereby, the light-shielding film 13 and the halftone film 12 in the opening region 10c shown in FIG. 2 are removed by etching. At this time, the etching selectivity is adjusted so that the high-sensitivity negative resist 14b in the halftone region 10b shown in FIG. 2 is also removed by etching. That is, by the dry etching in this step, the opening region 1
The light-shielding film 13 and the halftone film 12 of 0c are removed, and the high-sensitivity negative resist 14b of the halftone region 10b is also removed, exposing the light-shielding film 13b of the halftone region 10b. On the other hand, on the light-shielding film 13a in the light-shielding band region 10a, due to the difference in the resist film thickness, even after the dry etching in this step, the high-sensitivity negative resist 14a
Remains.

FIG. 4 shows HTP in the second etching step.
It is an outline sectional view of SM. After completion of the dry etching in the first etching step, wet etching is performed. Thereby, the halftone region 10b shown in FIG.
The exposed light shielding film 13b is removed. On the other hand, the light-shielding film 13a in the light-shielding band region 10a is not removed by wet etching because it is protected by the high-sensitivity negative resist 14a remaining after the dry etching in the first etching step.

FIG. 5 is a schematic sectional view of the HTPSM in the cleaning step. After removing the high-sensitivity negative resist 14a remaining on the light-shielding film 13a in the light-shielding band region 10a shown in FIG. 4, cleaning is performed. As described above, the HTPSM 10 in which the light shielding band 16, the halftone portion 17, and the opening 18 are formed on the quartz glass substrate 11 is manufactured.

According to the method of manufacturing the HTPSM 10 having the above-described steps, only one drawing step is required.
6. In order to form the halftone portion 17 and the opening 18, it is not necessary to repeat the development, etching, and cleaning steps following the drawing step. Therefore, H
The manufacturing process of the TPSM 10 is greatly reduced, and the time required for manufacturing can be shortened.

Further, since the drawing process is performed only once,
Unlike the related art, when performing the second writing, it is not necessary to consider a trouble in the writing process such as a displacement of the charge-up.

Further, since the number of manufacturing steps is greatly reduced, the risk of foreign matter adhering is reduced, and the occurrence of defects can be prevented. In the above description, the thickness of the high-sensitivity negative resist 14 is set so that the high-sensitivity negative resist 14b on the light-shielding film 13b in the halftone region 10b is removed by dry etching in the first etching step. Are set in accordance with the etching conditions. Also,
The thickness of the low-sensitivity negative resist 15 is set by dry etching and wet etching in the first and second etching steps so that the light-shielding film 13a in the light-shielding band region 10a is not exposed.

[0030]

As described above, according to the present invention, a high-sensitivity negative resist and a low-sensitivity negative resist are used for manufacturing a phase shift mask, and a high-sensitivity negative resist and a low-sensitivity negative resist are used in a light-shielding band region. And a high-sensitivity negative resist is exposed in the halftone region. As a result, the thickness of the resist in the halftone region after development is smaller than the thickness of the resist in the light-shielding band region. Further, by the dry etching of the opening region, the high-sensitivity negative resist in the halftone region is also removed to expose the light shielding film. At this time, the resist remains in the light-shielding band region to protect the light-shielding film. Therefore, the light shielding film in the halftone region is removed by wet etching, and the light shielding film in the light shielding band region remains.

Thus, the light-shielding band, the halftone portion, and the opening of the phase shift mask can be formed in one drawing process, so that the developing, etching, and cleaning steps following the drawing process are repeated. It is not necessary to perform the process, and the number of manufacturing steps is greatly reduced, so that the time required for manufacturing can be reduced.

Further, it is not necessary to consider a trouble in the drawing process such as a position shift due to charge-up at the time of performing the second drawing. In addition, since the number of manufacturing steps is greatly reduced, the risk of foreign matter adhering is reduced, and the occurrence of defects can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an HTPSM in a writing step.

FIG. 2 is a schematic sectional view of the HTPSM in a developing step.

FIG. 3 is a schematic sectional view of the HTPSM in a first etching step.

FIG. 4 is a schematic sectional view of the HTPSM in a second etching step.

FIG. 5 is a schematic sectional view of the HTPSM in a cleaning step.

FIG. 6 is a schematic cross-sectional view of the HTPSM in a conventional first writing step.

FIG. 7 is a schematic cross-sectional view of the HTPSM in a conventional first developing step.

FIG. 8 shows a conventional HTPSM in a first etching step.
FIG. 3 is a schematic sectional view of FIG.

FIG. 9 is a schematic cross-sectional view of the HTPSM in a first conventional cleaning step.

FIG. 10 is a schematic cross-sectional view of the HTPSM in a conventional second writing step.

FIG. 11 is a schematic cross-sectional view of the HTPSM in a second conventional developing step.

FIG. 12 shows HTPS in a conventional second etching step.
It is a schematic sectional drawing of M.

FIG. 13 is a schematic sectional view of the HTPSM in a second conventional cleaning step.

[Explanation of symbols]

10 Half-tone type phase shift mask (HTPS
M), 10a: light-shielding band area, 10b: halftone area, 10c: open area, 11: quartz glass substrate,
Reference numeral 12: halftone film, 13, 13a, 13b: light-shielding film, 14, 14a, 14b: high-sensitivity negative resist, 15, 15a: low-sensitivity negative resist.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03F 7/40 521 G03F 7/40 521 H01L 21/027 H01L 21/30 502P F-term (Reference) 2H025 AA02 AB08 AC06 AD01 BC13 BC42 CA00 DA13 DA19 DA30 DA31 DA40 FA10 FA40 FA41 FA50 2H095 BB03 BB10 BB15 BB16 BB19 BC05 BC08 BC27 2H096 AA24 CA05 CA06 CA20 EA06 EA23 HA17 HA23 HA30 KA04 KA05

Claims (4)

[Claims] 1. A method of manufacturing a phase shift mask having a light-shielding band, a halftone portion, and an opening, comprising: forming a halftone film, a light-shielding film, a high-sensitivity negative resist, and a low-sensitivity negative resist on a substrate. The high-sensitivity negative resist and the low-sensitivity negative resist in the light-shielding band region, which is a region to be the light-shielding band, and the high-sensitivity negative resist in the halftone region, which is the region to be the halftone portion Are exposed at a predetermined exposure amount, and after development, the light-shielding film and the halftone film in the opening region that is the region to be the opening by dry etching, and the high-sensitivity negative resist in the halftone region. And removing the light shielding film in the halftone region by wet etching. 2. The method according to claim 1, wherein after removing the light shielding film in the halftone region by wet etching, the resist in the light shielding band region is removed and washed.
A manufacturing method of the phase shift mask described in the above. 3. The method according to claim 1, wherein the substrate is made of quartz glass. 4. The method according to claim 1, wherein the light shielding film is made of chromium.