JPH0992599A - Manufacture of x-ray exposure mask, x-ray exposure method and device by use thereof, manufacture of semiconductor device with them, and semiconductor device formed with them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a pattern which generates a phase shift to be optionally set in position and size by a method wherein a drawing operation is carried out with an electron beam varying exposure, and the pattern is formed through a development/ plating process and/or a development etching process. SOLUTION: A plating electrode layer 2 and a positive resist layer 3 are applied onto the surface of a mask board 1. A pattern is drawn by an electron beam 4 satisfying a formula, Da<Db, wherein Da represents the exposure of the periphery A of the pattern, and Db is the exposure of the center B of the pattern. Then, a developing operation is carried out setting an exposure time so as to enable resin to be completely removed from the center B but left unremoved in the periphery A. Then, a plating operation is carried out, a pattern 7 is formed only on the center B where the plating electrode layer 2 is exposed, an additional development operation is carried out, resist is completely removed from the periphery A to make the plating electrode 2 exposed, and a following plating process is carried out to form a pattern 7 in the periphery A. A resist 3 is removed by etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a mask used for X-ray exposure and a semiconductor device manufactured using the same.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductor integrated circuits, there has been proposed a method of transferring a desired pattern by using an X-ray in the proximity of an X-ray mask to an object to be transferred. In this method, the pattern on the X-ray mask is transferred onto the wafer, but the resolution of the transferred pattern deteriorates due to diffraction. X
Since the wavelength of the line is small and its change is not large, the desired pattern can be transferred by determining the pattern of the X-ray mask in consideration of the deterioration amount. However, when a finer pattern is transferred, it is not possible to deal with the deterioration of the transfer pattern simply by changing the pattern size of the X-ray mask.

Therefore, a method has been proposed in which the cross-sectional shape of the pattern of the X-ray mask is changed and the phase of the X-ray at the end of the pattern is shifted to reduce deterioration of resolution. This mask for shifting the phase is called a phase shift type mask, and there is a method of changing the thickness of the absorbing material at the end of the pattern or attaching a material for shifting the phase to the end of the pattern.

A conventional method for producing these two types of phase shift masks will be described below. Japanese Patent Laid-Open No. 5-3146 describes
A method of making an X-ray mask having a phase shifter material made of a material different from the X-ray absorbing material at the end of the pattern is shown.

According to the conventional example, as shown in FIG.
After a pattern 7 made of an X-ray absorbing material is formed on the X-ray transparent substrate 1, a phase shift layer having a refractive index different from that of the absorber by chemical vapor deposition on the entire surface of the pattern 7 as shown in FIG. 10-2. By manufacturing 11 and performing anisotropic etching as shown in FIG. 10C, the phase shift layer 11 can be removed by rubbing only the side wall of the pattern 7, and an X-ray mask having a desired shape can be completed. .

Further, Japanese Patent Laid-Open No. 5-13310 describes a method of manufacturing X-ray masks having different thicknesses of X-ray absorbing materials. According to this, as shown in FIG.
A layer 1 to be the X-ray transparent film SiN is formed on the i substrate 14, and a Si substrate etching mask layer 15 is formed on the back surface. On the X-ray transparent film layer 1 and SiN, a Ta layer 7 which is an X-ray absorbing material layer, a SiO ₂ layer 13 which is an etching mask layer, and a resist layer 3 which is a photosensitive layer are formed thereon. Then, the resist layer 3 is exposed and developed in a shape corresponding to the pattern dimension L1 in which the thin portion and the thick portion of the completed absorber are combined.

As shown in FIG. 11B, the etching mask layer 13 is etched using the resist layer 3 as a mask. Further, the X-ray absorbing material layer Ta7 is etched using the etching mask layer 13 as a mask (FIG. 11-3). Next, we etching the etching mask SiO ₂ layer 13 as an etching mask SiO ₂ layer 13 is the shape of the pattern matches the pattern dimension L2 of the thick film (Figure 11-
4). Then, the X-ray absorbing material layer Ta layer 7 is etched again using the etching mask layer 13 as a mask (FIG. 11-
5). After the desired pattern shape is obtained in this manner, the etching mask layer 15 is processed so that the Si substrate 14 serves as a support frame for the X-ray transparent film, and then the Si substrate 14 is etched from the back surface, and the X-ray is further processed. The etching mask layer 13 of the absorption layer 7 is removed to complete the phase shift mask (FIG. 11-6).

These manufacturing methods have the drawback that the position and size of the pattern that causes the phase shift cannot be set arbitrarily.

[0009]

SUMMARY OF THE INVENTION The present invention has been described with respect to a method of manufacturing a phase shift type X-ray mask which solves the above-mentioned drawbacks of the conventional method.

[Means for Solving the Problems]

According to the present invention, the difference between the developing rates is 2
Drawing with an electron beam at a step exposure amount, and then developing so that the resist is removed only in the area with a large exposure amount,
It is to provide a method for forming patterns of two kinds of thickness by performing development and plating again after plating and forming a pattern. Further, the present invention further provides a method applicable to a method using etching other than plating and a method applicable to the production of an X-ray mask in which the thickness of the absorber outside the exposure region is thicker than that inside the exposure region. To provide.

That is, the present invention is characterized in that the exposure amount is set to a plurality of values at the time of electron beam writing and writing is performed, and a pattern is formed by a developing / plating step, a developing / etching step, or both steps. It is to provide a method for manufacturing an X-ray exposure mask.

Further, there is provided a method for producing an X-ray exposure mask, characterized in that the exposure amount is changed depending on any one of a writing time, a number of times of writing, an electron beam current amount at the time of writing, or a combination thereof.

The X-ray exposure mask manufacturing method of the present invention is characterized in that the developing and plating steps are repeated a plurality of times, and the etching step is repeated a plurality of times. Another object of the present invention is to provide a method for producing an X-ray exposure mask, which is characterized by repeating the etching process a plurality of times.

Further, the present invention provides a method for producing an X-ray exposure mask, characterized in that the development and plating steps are repeated a plurality of times, wherein the X-ray absorption layer is formed between the development and X-ray absorption layer plating steps. Another object of the present invention is to provide a method for producing an X-ray exposure mask, which comprises the step of plating the plating inhibiting layer.

The present invention is also that the X-ray exposure mask is a phase shift type X-ray mask.

The present invention further provides an X-ray exposure apparatus using the X-ray exposure mask produced by any of the above methods.

The present invention further provides an X-ray exposure method using the X-ray exposure mask produced by any one of the above methods.

Further, the present invention provides a semiconductor device manufactured by using the X-ray exposure mask manufactured by any one of the above methods and a manufacturing method thereof.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention can be applied to various X-ray exposure masks in which the thickness and material of the absorber are different, but the X-ray phase shift masks (Examples 1 to 7) and the absorber in the exposure region can be used. In comparison, an X-ray mask (Example 7) having a thick absorber around the exposure region will be described.

[Description of X-ray Phase Shift Mask] An example of the structure of a general phase shift X-ray mask will be described with reference to FIG. The mask substrate 1 is required to sufficiently transmit X-rays and to stand by itself, and it is desirable that the mask substrate 1 has a thickness within a range of 0.1 to 10 μm.
In addition to inorganic films of N, SiC, SiCN, BN, AlN,
It is composed of a known material such as an organic film such as polyimide or a composite film of these. Next, the X-ray absorber 7 as an X-ray pattern is composed of a heavy metal such as Au, W, Ta, Pt, or a compound thereof as a film that sufficiently absorbs X-rays and has good workability. The holding frame 12 for holding the mask substrate 1 is made of single crystal Si. further,
The X-ray mask may be provided with a protective film for the X-ray absorber and an antireflection film for alignment light.

Next, the effect of the phase shift will be described. In this mask, the thickness of the pattern end is d1 and is thinner than the center thickness d2. The X-rays transmitted through these regions are X1 and X2, respectively, and the phase difference between the X-rays of X1 and X2 is determined. Δφ
Is necessary, and preferably π is
The resolution performance is improved. The phase difference Δφ is the film thickness difference (d2-d
1) and exposure wavelength λ, the refractive index n of the absorber with respect to the exposure wavelength
It can be expressed as follows.

Δφ = (n-1) * (d2-d1) * 2 * π / λ When the phase difference Δφ is π and Au is used as the X-ray absorbing material, the film thickness difference (d1-d2) is approximately 0. It will be .36um. Therefore, if the thickness (d2) of the large absorber pattern is 0.7 μm, the film thickness at both ends of the pattern should be half that thickness.

Further, in the case of a mask which causes a phase shift effect by attaching a member that causes a phase shift to the end of the pattern, if the absorbing material 7 and the real part of the refractive index are different materials as the phase shift material. Well, not necessarily the absorber 7
It is not necessary to use a material having a large X-ray absorption rate as in the above.

The method of the present invention is characterized in that the exposure amount is set to a plurality of values at the time of electron beam writing and writing is performed, and the pattern is formed by the developing / plating step, the developing / etching step, or both steps. This is a method for producing an X-ray exposure mask.

There are no particular restrictions on the means for setting the exposure amount to a plurality of values when writing with an electron beam. For example, the exposure amount D has a relationship of D∝ (1 / v) · I · n depending on the scanning speed v of the electron beam, the number of drawing times n, and the electron beam current amount I at the time of drawing. increase,
It can be seen that the exposure amount is increased by increasing the number of drawing times.

The X-ray exposure mask of the present invention can be used in an ordinary X-ray exposure apparatus or exposure method. For example, in the exposure apparatus for manufacturing a minute device as shown in FIG. 12 (Embodiment 8). It can be used as the mask E, and thereby a semiconductor device, a thin film magnetic head microsyringe, etc. can be efficiently and accurately manufactured.

[0027]

【Example】

First Embodiment FIG. 1 shows an embodiment of the present invention. A method of drawing with an electron beam and forming an absorber by plating to form a pattern with a thin film thickness around the periphery is shown. 1 to FIG.
1 to FIG. 1-6 will be described separately for each step.

First step (FIG. 1-1): Mask substrate 1
Is a thin film material that is transparent to X-rays, eg SiN 2um
Further, the mask substrate 1 is supported by a holding frame 12, and the surface of the mask substrate 1 is Au 0.05 um.
The plated electrode layer 2 is previously vapor-deposited. Further, a positive resist layer 3 having a thickness of 1 μm is applied on the plated electrode layer 2. With the electron beam 4, the exposure amount is D at the center B (exposure amount Db) and the periphery A (exposure amount Da) of the pattern.
Drawing is performed so that a <Db. Second step (FIG. 1-2): The development characteristics of the positive resist (PMMA) with respect to the electron beam at an acceleration voltage of 20 kV are shown in FIG. The vertical axis represents the developing speed and the horizontal axis represents the electron beam exposure amount. From FIG. 9, the developing speed of the A part is smaller than that of the B part. The developing time Td is set so that the resist in the B part is completely removed, but the resist in the A part remains. That is, the development time is set such that To / Ra <Td <To / Rb, where To is the initial film thickness of the resist. Where Ra and Rb
Are the developing speeds corresponding to the exposure amounts Da and Db, respectively. After the development, the resist in the part B is removed and the plated electrode layer 2
However, since the resist in the portion A has a small exposure amount, the film thickness of the resist is reduced, but the resist is not completely removed and remains. Third step (FIG. 1-3): When plating is performed in the state shown in FIG. 1-2, since the plating electrode layer is not exposed in the A part, Au is not plated, and only the B part is plated with Au. Is formed. Fourth step (FIG. 1-4): Additional development is performed to completely remove the resist in the portion A to expose the plated electrode layer 2. Fifth step (FIG. 1-5): plating is performed again to form a pattern on the A portion. Sixth step (FIGS. 1-6): The resist is removed by wet etching or dry etching to obtain a desired pattern. After that, the plating electrode layer 2 is removed if necessary.

In the present embodiment, the electron beam exposure amount can be changed by changing the drawing time, the number of times of drawing, the electron beam current amount at the time of drawing, or a combination thereof. Further, since it suffices to perform the exposure so that there is a difference in the exposure amount between the A portion and the B portion, the exposure may be performed using X-rays or light in addition to the electron beam exposure.

Second Embodiment In the first embodiment, Au is also formed on and around the pattern of the B portion previously formed when the A portion is plated as shown in FIG. 1-5.
May be plated, making it difficult to control the film thickness. In this embodiment, in such a case, the pattern of the B portion previously formed is prevented from being re-plated. The steps up to the third step (FIGS. 2-3) are the same as those in the first embodiment, and will be described from the fourth step. Fourth step (FIG. 2-4): The developing time is set so that the resist is slightly left on the portion A, and the resist is developed. Fifth step (FIG. 2-5): Next, the plating inhibiting layer 5 is formed on the surface of the pattern of the B part by plating. The plating inhibiting layer 5 is made of Ni or the like, and since the surface of Ni is oxidized, the pattern material Au is not plated on the surface. Sixth step (FIG. 2-6): Additional development is performed to completely remove the resist in the portion A to expose the plated electrode layer 2. Seventh step (FIGS. 2-7): plating is performed again to form a pattern in the A portion so as to have a desired thickness. in this case,
Because of the plating inhibiting layer 5, the pattern surface of the previously plated portion B is not plated. Eighth step (FIGS. 2-8): The resist is removed by wet etching or dry etching to obtain a desired pattern.

In the present embodiment, the absorbers made of the same material were plated in the portions A and B, but it is possible to form the patterns by plating the absorbers made of different materials. After that, the plating electrode layer 2 is removed if necessary.

Third Embodiment In this embodiment, a method of separating the portion A and the portion B and forming another material will be described. A method of forming the same quality pattern by separating the A part and the B part is also possible in the first embodiment,
When forming different materials, this embodiment is suitable. The steps up to the third step (FIG. 3-3) are the same as those in the first embodiment, and will be described from the fourth step. Fourth step (FIG. 3-4): Next, the plating inhibiting layer 5 is formed on the surface of the pattern of the B portion. The plating inhibition layer 5 is Ni
And the pattern material A is formed on the surface of the plating suppressing layer 5.
u is not plated. Fifth step (FIG. 3-5): Additional development is performed to completely remove the resist in the portion A to expose the plated electrode layer 2. Sixth step (FIG. 3-6): A material having a desired material is plated on the A portion so as to have a desired thickness to form a pattern. In this case, because of the plating-inhibiting layer 5, the back surface of the pattern of the previously plated portion B is not plated. Seventh step (FIGS. 3-7): The resist is removed by wet etching or dry etching to obtain a desired pattern. After that, the plating electrode layer 2 is removed if necessary.

Fourth Embodiment This embodiment shows a method applicable to the case where the size of the thin film, that is, the pattern dimension da of the A portion is small. The first step is the same as in the first embodiment. Second step (FIG. 4-2): The plating electrode layer 2 of the B portion is exposed, and further development is performed so that the resist thickness of the A portion becomes the pattern film thickness difference between the A portion and the B portion. Third step (FIG. 4-3): Plate to a desired absorber thickness. Fourth step (FIG. 4-4): Removal by wet etching or the like to obtain a desired pattern.

Fifth Embodiment In this embodiment, a case where the present invention is applied to a method of forming a pattern using etching will be described. First step (FIG. 5-1): absorber 7 on mask substrate 1
W is vapor-deposited, and the positive resist layer 3 is applied on the absorber. Drawing is performed by the electron beam 4 so that the exposure amount becomes Da <Db in the B portion (exposure amount Db) and the A portion (exposure amount Da). However, the C portion is not exposed. Second step (FIG. 5-2): The resist in the part B is completely removed, and the developing time is adjusted so that the resist in the part A remains with an appropriate thickness. Third step (FIG. 5-3): When the absorber 7 is etched from above by anisotropic dry etching, the absorber does not become smaller in the lateral direction but is etched only in the thickness direction of the absorber. When the etching rate of the resist is equal to that of the absorber, the absorber is etched while maintaining the shape of the resist. Fourth step (FIG. 5-4): Further, when the etching is continued, the pattern of the B portion is completely removed, the absorbent material of the A portion is also etched and thinned, and the peripheral absorbent material has a thin pattern. In the present embodiment, the description has been made assuming that the resist and the absorber have the same etching rate, but if they differ, the exposure amounts Da and Db or the developing time in step 2 is adjusted to control the remaining resist film thickness in step 2. However, the shape of the final absorbent in step 4 can be controlled. Further, although a positive type resist is used in this embodiment, a negative type resist may be used.

Sixth Embodiment In this embodiment, a method of forming a pattern using both etching and plating will be described. First step (FIG. 6-1): The plating electrode layer 2 and the absorber 7 are vapor-deposited on the mask substrate 1, and the positive resist layer 3 is further applied on the absorber. Electron beam 4
Thus, the B portion (exposure amount Db) and the A portion (exposure amount Da) are drawn so that the exposure amount becomes Da <Db. However, C
Parts shall not be exposed. Second step (FIG. 6-2): The resist of part B is completely removed, and the developing time is set so that the resist of part A remains with an appropriate thickness. Third step (FIG. 6-3): The absorber 7 is etched from above by anisotropic dry etching to expose the plated electrode layer 2. Fourth step (FIG. 6-4): A material having a desired material is plated on the B portion so as to have a desired thickness to form the pattern 9. Fifth step (FIG. 6-5): The absorber 7 is etched from above by anisotropic dry etching to completely remove the absorber in the portion A. Here, the etching is pattern 9
It is preferable that the absorbing material 7 is etched by a higher etching rate.

Although a positive type resist is used in this embodiment, a negative type resist may be used.

Seventh Embodiment The present invention can be applied to a case where the absorber in the region outside the exposure region where X-rays should be completely shielded is made thicker than the absorber of the pattern in the exposure region. FIG. 7 of the present embodiment
In the production of an X-ray mask in which the thickness of the absorber of the pattern in the exposure region is uniform as shown in 1, the absorbers of two kinds of thicknesses exist as a whole, and the resist outside the exposure region is present. The exposure amount is set to Db and the exposure amount of the resist in the exposure region is set to Da, and the exposure is the same as in the first embodiment. In this case, a resist that is sensitive to a plurality of energy beams such as light and electron beams may be used, and the exposure outside the exposure area may be performed using another energy beam.

Further, in the preparation of an X-ray mask having two types of absorber thicknesses in the pattern of the exposure area as shown in FIG. 7B, absorber patterns of three types of thickness are mixed. , In that case, the exposure amount at the time of electron beam drawing is 3
It is possible to obtain an X-ray mask having a pattern of three kinds of desired thickness by setting the stage and repeating the steps of development and plating three times.

Eighth Embodiment Next, an embodiment of an exposure apparatus for manufacturing a minute device (semiconductor device, thin film magnetic head, micromachine, etc.) using the above-described mask will be described. FIG. 12 is a view showing the arrangement of the X-ray exposure apparatus according to this embodiment. SR radiation, A in the figure
The sheet-beam-shaped synchrotron radiation B radiated from the device is expanded by the convex mirror C in a direction perpendicular to the plane of the radiation beam. The emitted light reflected and expanded by the convex mirror C is adjusted by the shutter D so that the exposure amount in the irradiation area becomes uniform, and the emitted light that has passed through the shutter D is guided to the X-ray mask E. The X-ray mask E is manufactured by the method described in any of the embodiments described above. The exposure pattern formed on the X-ray mask E is exposed and transferred onto the wafer F by a step & repeat method, a scanning method, or the like.

Ninth Example Next, an example of a method of manufacturing a semiconductor device using the above-described X-ray mask structure will be described. FIG. 13 is a flowchart showing a manufacturing flow of semiconductor devices (semiconductor chips such as IC and LSI, liquid crystal panels, CCDs, thin film magnetic heads, microsyringes, etc.). In step 1 (circuit design), the circuit of the semiconductor device is designed. In step 2 (mask fabrication), an X-ray mask structure having the designed circuit pattern is manufactured using the method of Examples 1 to 7. On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by the X-ray lithography technique using the X-ray mask structure and the wafer prepared above. The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer manufactured in step 4, such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), etc. including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, the semiconductor device is completed,
This is shipped (step 7).

FIG. 14 shows the detailed flow of the wafer process. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted in the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the X-ray exposure method described above. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), the resist that is no longer needed after etching is removed.
By repeating these steps, multiple circuit patterns are formed on the wafer.

[0042]

As described above, according to the present invention, the phase shift material can be easily manufactured at an arbitrary position and size which have been difficult in the past. Furthermore, the manufacturing method of the present invention enables the manufacture of highly accurate semiconductor devices.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention.

FIG. 3 is a diagram showing an embodiment of the present invention.

FIG. 4 is a diagram showing an embodiment of the present invention.

FIG. 5 is a diagram showing an embodiment of the present invention.

FIG. 6 is a diagram showing an example of the present invention.

FIG. 7 is a diagram showing an example of the present invention.

FIG. 8 is a diagram showing a configuration of a phase shift mask.

FIG. 9 is a diagram showing development characteristics of a PMMA resist.

FIG. 10 is a diagram showing a method of manufacturing a conventional phase shift mask.

FIG. 11 is a diagram showing a method of manufacturing a conventional phase shift mask.

FIG. 12 is an exposure apparatus using the phase shift mask of the present invention.

FIG. 13 is a diagram showing a process of manufacturing a device by a process using the phase shift mask of the present invention.

FIG. 14 is a diagram showing a process for producing a device by a process using the phase shift mask according to the present invention.

[Explanation of symbols]

 1 Mask Substrate 2 Plating Electrode Layer 3 Resist 4 Electron Beam 5 Plating Suppression Layer 7 X-ray Absorber Layer 8 X-ray Absorber for Blocking X-rays Outside the Exposure Area 11 Phase Shift Film 12 Holding Frame 13 Etching Mask Layer 14 Si Substrate 15 Etching mask layer A SR Radiation source B Synchrotron radiation C Convex mirror D Shutter E X-ray mask

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/30 531E

Claims (10)

[Claims] 1. An X-ray exposure wherein an exposure amount is set to a plurality of values when writing with an electron beam and writing is performed, and a pattern is formed by a developing / plating step, a developing / etching step, or both steps. For making masks for use. 2. The method of manufacturing an X-ray exposure mask according to claim 1, wherein the exposure amount is changed depending on any one of a writing time, a number of times of writing, an electron beam current amount at the time of writing, or a combination thereof. 3. The method for producing an X-ray exposure mask according to claim 1, wherein the steps of developing and plating are repeated a plurality of times. 4. The method for manufacturing an X-ray exposure mask according to claim 1, wherein the etching step is repeated a plurality of times. 5. The method of manufacturing an X-ray exposure mask according to claim 3, further comprising a plating step of a plating inhibiting layer of the X-ray absorption layer between the development and X-ray absorption layer plating steps. . 6. The method for producing an X-ray exposure mask, wherein the mask produced in claim 1 is a phase shift type X-ray mask. . 7. An X-ray exposure apparatus using the X-ray exposure mask manufactured according to claim 1. 8. An X-ray exposure method using the X-ray exposure mask produced according to claim 1. 9. A semiconductor device manufactured using the X-ray exposure mask manufactured according to claim 1. 10. A method of manufacturing a semiconductor device, wherein the X-ray exposure mask manufactured according to claim 1 is used.