GB2233117A - X-ray mask - Google Patents
X-ray mask Download PDFInfo
- Publication number
- GB2233117A GB2233117A GB8915049A GB8915049A GB2233117A GB 2233117 A GB2233117 A GB 2233117A GB 8915049 A GB8915049 A GB 8915049A GB 8915049 A GB8915049 A GB 8915049A GB 2233117 A GB2233117 A GB 2233117A
- Authority
- GB
- United Kingdom
- Prior art keywords
- mask
- ray
- pattern
- conducting film
- base plate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000004065 semiconductor Substances 0.000 claims abstract description 10
- 239000000758 substrate Substances 0.000 claims abstract description 3
- 239000004411 aluminium Substances 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 2
- 230000007547 defect Effects 0.000 abstract description 11
- 238000010894 electron beam technology Methods 0.000 abstract description 10
- 229910052751 metal Inorganic materials 0.000 abstract description 5
- 239000002184 metal Substances 0.000 abstract description 5
- 229910004205 SiNX Inorganic materials 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 11
- 238000007689 inspection Methods 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 7
- 238000002834 transmittance Methods 0.000 description 7
- 238000001015 X-ray lithography Methods 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000013507 mapping Methods 0.000 description 3
- 229910019567 Re Re Inorganic materials 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 2
- 238000000609 electron-beam lithography Methods 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 238000000206 photolithography Methods 0.000 description 2
- 229920002120 photoresistant polymer Polymers 0.000 description 2
- 230000006798 recombination Effects 0.000 description 2
- 238000005215 recombination Methods 0.000 description 2
- 238000007493 shaping process Methods 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/06—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials
- H01L21/08—Preparation of the foundation plate
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/22—Masks or mask blanks for imaging by radiation of 100nm or shorter wavelength, e.g. X-ray masks, extreme ultraviolet [EUV] masks; Preparation thereof
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Preparing Plates And Mask In Photomechanical Process (AREA)
- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
- Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
Abstract
An X-ray mask for producing micro scale images on semiconductor substrates is constituted such that a grounded charge conducting film 30, e.g. Al, is deposited between X-ray transmissive base plate 20 e.g. SiC or SiNx and an X-ray absorbing image 40, e.g. metal to absorb the charges accumulated around the X-ray absorbing image, thereby making it possible to correctly inspect the line width and defects of the pattern of the mask. The charges accumulated around the X-ray absorbing image in the prior art make the scanning electron beams deflected so that correct measuring of the pattern of the mask becomes impossible. Therefore, the charge conducting film which is grounded absorbs the produced charges before they accumulate, thereby keeping the scanning electron beams from being deflected, and ultimately making it possible to measure the pattern of the mask correctly. <IMAGE>
Description
X-RAY MASK
The present invention relates to an X-ray lithography mask for mapping the structural shapings of circuits onto a wafer in manufacturing ultra-high density semiconductor devices, and particularly to an X-ray mask in which the structure is improved in such a manner that the mask having a structure of a fine pattern of a fraction of a micron can be checked as to its line widths and as to the existence of any defects.
In the manufacture of semiconductor devices, a minute pattern up to line widths of 0.1 to 1 microns is required, and in accordance with the recent trend of increasing density of semiconductor devices, the line widths are actually attaining these dimensions.
Therefore, in order to cope with the sub-micron scale pattern which the general photolithography cannot cope with, electron beam lithography or X-ray lithography have come to be used recently, in which electron beams or X-rays are respectively used as the exposure beam means.
The electron beam lithography is a kind of image scanning method for depositing directly the reduced patterns onto the semiconductor substrate without using a mask, but this method has the disadvantages that the device is costly and complicated, and its productivity is very low. On the other hand, the X-ray lithography using a soft x-ray scanning source has the advantages that its pattern shaping method is similar to that of the usual photolithography, its structure is simple making it convenient to use and its production yield is very high.
An example of such an X-ray lithography system is U.S.
Patent No.3,783,824 (issued on March 25, 1975) which is schematically illustrated in Figure 1, and its image mapping process will be briefly described below.
Electron beams 12 emitted by an electron source 11 hit the desired portions of an X-ray target 13, and the said target 13 emits X-rays upon interaction with the incident electrons. Here, the released X-rays are soft xrays 15 with the wave length of 4 to 9 A and with a good transmissibility, the said interactions being carried out under a high vacuum state.
Further, the soft X-rays 15 emitted from the X-ray target 13 are introduced through a transparent window 14 to a low vacuum space where a mask 16 and a wafer 18 are disposed adjacently with a predetermined spacing therebetween. The soft X-rays 15 thus introduced into the low vacuum space will either pass through the mask 16 or will be absorbed into the mask 16 in accordance with the pattern of the mask, so that the pattern of the mask 16 will be reproduced on the wafer 18 where a photoresist film 17 is coated.
In such an X-ray lithography for mapping the image of the mask by means of X-rays, the quality of the X-ray mask 16 having a pattern of sub-micron scale is directly related to the fineness and precision of the pattern of semiconductor devices. Therefore, the process of checking the line widths and defects of the pattern of the mask is closely related to the ultimate characteristics and production yield of the semiconductor device.
As shown in Figure 2A, a thin X-ray transparent base plate 2 for transmitting X-rays is mounted on a ring type frame 1 which support & he whole mask, and an X-ray absorbing layer 3 for blocking the X-rays is disposed in a desired pattern on the base plate 2. The X-ray mask thus constituted has to undergo an inspection process for checking the desired pattern and arrangement state, for measuring the dimension of the line widths, and for making a judgment on the properness of proceeding to the next step, before the said mask undergoes the process of reproducing the fine pattern onto the wafer.
The X-ray mask has line widths of less than 0.5 microns as mentioned above, and therefore, the checking of line widths and defects is carried out by means of an electron microscope unlike in the case of the conventional photo mask.
Figure 2B illustrates schematically the checking process for line widths and defects by means of an electron microscope in the conventional X-ray mask, and this mask has an inherent problem due to its constitution. That is, the X-ray absorbing layer 3 arranged in the shape of stripes on the X-ray transparent base plate 2 made of an insulator is made of a thin metal plate such as gold, and therefore, the surrounding space of the X-ray absorbing layer 3 is charged with negative electric charges e due to the electron beams 5 from the scanning electron microscope. Due to such electric charges e which are produced during the inspection,the scanning electron beams 5 are deflected, and therefore, the ability of exact inspections for the pattern can be lost.Thus, it becomes impossible to detect and remove the defects arising during the manufacturing and use, and the measuring of the line widths cannot be properly carried out.
Therefore it is the object of the present invention to provide an X-ray mask of a novel structure, in which the misleading of the inspection judgment due to the electric charges accumulated during the inspection of line widths and defects of the X-ray mask by means of an electron microscope can be removed, and ultimately, the production yield of semiconductor devices can be improved.
In achieving the above object, the device of the present invention is constituted such that a conductive thin metal film is deposited on the base plate of the mask, so that it can constitute an electric charge removing means for removing the electric charges before their accumulation during the inspection.
Brief descriDtion of the drawings
The above object and other advantages of the present invention will become more apparent by describing a preferred exemplary embodiment of the present invention with reference to the attached drawings in which;
Figure 1 is a schematic illustration of the usual Xray lithography system;
Figure 2A is a sectional view showing the structure of the conventional X-ray mask;
Figure 2B is a schematic view showing the inspection process for line widths and defects in the conventional Xray mask;
Figure 3A is a sectional view showing the structure of the X-ray mask according to the present invention; and
Figure 3B is a schematic illustration showing the inspection process for line widths and defects using an electron microscope according to the present invention.
Figure 3A shows the structure of an X-ray mask provided with a charge removing means according to the present invention. In this drawing, reference number 10 indicates a frame for protecting and supporting an X-ray transparent base plate 20, and the said frame 10 is formed in a ring type, and is made of a material having a high endurability and a high dimensional stability such as Si or glass.
The said base plate 20 has the function of supporting an X-ray absorbing layer 40 to be formed later, and is mounted upon the said frame 10. The said base plate 20 is made of a material which has a high X-ray transmittance, and which is similar to the materials of the X-ray absorbing layer 40 and the frame 10 in its physical characteristics such as thin Sic or SiNx. Actually, the said base plate 20 has to pass the soft X-rays by over 50%.
A charge conducting film 30 is deposited on the said base plate 20 in a predetermined thickness, and is made of a thin metal having a much lower X-ray absorptance such as aluminium, its required thickness being different depending on the material used, but preferably 1/100 of the X-ray absorbing layer 40 (about 0.005 micron).
Here, one important fact is that the charge conducting film 30 is grounded so that, of the total landing charges, excluding the charges disappearing through recombination, the remaining charges could not exert repulsing forces against the incoming electron beams.
The X-ray absorbing layer 40 which is deposited in the shape of stripes upon the said charge conducting film 30 is composed of a high atomic number metal having a high X-ray absorptance in a predetermined thickness (about 0.5 micron), and this layer 40 serves as a pattern of the mask for blocking X-rays.
A part of the X-rays emitted from the X-ray target 13 of Figure 1 is absorbed into the X-ray absorbing layer 40, and the remaining portions of the X-rays pass through both the charge conducting film 30 and the base plate 20, so that the pattern of the mask should be reproduced on a wafer 18 on which a photoresist film 17 is deposited.
Figure 3B illustrates schematically the process of inspecting the X-ray mask of Figure 3A by means of an electron microscope in order to detect the line widths and defects of the pattern of the mask by scanning with electron beams 50 from an electron microscope.
Here, the electric charges produced in the space around the X-ray absorbing layer 40 due to the incoming electron beams 50 are dissipated through the recombination with the charge conducting film 30 before being accumulated to a substantial amount, while the excess charges are sunk into the ground. Accordingly, the incoming electron beams 50 can scan the pertinent areas without receiving any impediment.
Meanwhile, in the case of the X-ray mask provided with a charge removing means according to the present invention, the expected reduction of the transmittance due to the increase of the thickness of the mask will be negligible.
That is, the transmittance Tm for the whole mask can be defined;
-ud
Tm = e where u represents the transmission coefficient, and d the thickness of the medium. Therefore, the contributions of transmittance to the different layers of the mask can be compared as follows.
The transmittance T20 of the base plate 20 will be;
-2
T20 = Re where R is a constant. The transmittance T30 of the charge conducting film 30 will be;
-1
T30 = Re
The transmittance T40 of the X-ray absorbing layer 40 will be;
-100
T40 = Re
For, if it is assumed that the transmission coefficient of
T20 is 1, and that its thickness is 2, then the transmission coefficient of T30 will be 100 to 200, its thickness will be 1/100 to 1/200, the transmission coefficient of T40 will be 100 to 200, and its thickness will be 1 to 0.5.
Therefore, as shown in Table 1 below, the modulated transfer function MTF for the mask is not lagging behind that of the conventional ones.
Table 1 Modulated transfer function of mask
Modulated transfer function of mask
Conventional Present invention
Conventional Present invention -100 -100
Re Re
MTF = ---------------- MTF = --------------------
-2 -100 -3 -100
Re + Re Re + Re
According to the device of the present invention as described above, the line widths and defects on the high precision and high fineness pattern of the X-ray mask can be precisely inspected and detected, with the result that the reliability and production yield of the semiconductor device can be improved.
Claims (4)
1. An X-ray mask for producing micro scale fine images on semiconductor substrates, comprising;
a thin charge conducting film deposited on an X-ray transparent base plate under an X-ray absorbing layer of the mask and adapted to be grounded.
2. The X-ray mask as claimed in claim 1, wherein said charge conducting film is composed of aluminium.
3. The X-ray mask as claimed in claim 1 or 2, wherein
the ratio between the thicknesses of said base plate, said charge conducting film and said X-ray absorbing layer is 2 : (0.01-0.005) : (1-0.5).
4. An X-ray mask substantially as hereinbefore described
with reference to Figs. 3A and 3B of the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019890005232A KR920010065B1 (en) | 1989-04-20 | 1989-04-20 | X-ray mask |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8915049D0 GB8915049D0 (en) | 1989-08-23 |
| GB2233117A true GB2233117A (en) | 1991-01-02 |
Family
ID=19285513
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8915049A Withdrawn GB2233117A (en) | 1989-04-20 | 1989-06-29 | X-ray mask |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPH02296244A (en) |
| KR (1) | KR920010065B1 (en) |
| GB (1) | GB2233117A (en) |
| NL (1) | NL8901516A (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1499294A (en) * | 1975-06-30 | 1978-01-25 | Ibm | Manufacture of masks |
| GB1507752A (en) * | 1974-07-19 | 1978-04-19 | Ibm | X-ray mask |
| EP0097764A1 (en) * | 1982-06-30 | 1984-01-11 | International Business Machines Corporation | X-ray lithographic mask |
| GB2148540A (en) * | 1983-09-26 | 1985-05-30 | Canon Kk | Lithographic mask |
| US4528071A (en) * | 1983-10-25 | 1985-07-09 | Siemens Aktiengesellschaft | Process for the production of masks having a metal carrier foil |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57193031A (en) * | 1981-05-22 | 1982-11-27 | Toshiba Corp | Manufacture of mask substrate for exposing x-ray |
| JPS592324A (en) * | 1982-06-28 | 1984-01-07 | Nec Corp | X-ray exposure mask |
| JPS62282432A (en) * | 1986-05-31 | 1987-12-08 | Canon Inc | Mask for x-ray exposure and aligner |
| JPH07111946B2 (en) * | 1987-05-29 | 1995-11-29 | 株式会社日立製作所 | X-ray exposure mask pattern inspection method |
-
1989
- 1989-04-20 KR KR1019890005232A patent/KR920010065B1/en not_active IP Right Cessation
- 1989-06-06 JP JP1142288A patent/JPH02296244A/en active Pending
- 1989-06-15 NL NL8901516A patent/NL8901516A/en not_active Application Discontinuation
- 1989-06-29 GB GB8915049A patent/GB2233117A/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1507752A (en) * | 1974-07-19 | 1978-04-19 | Ibm | X-ray mask |
| GB1499294A (en) * | 1975-06-30 | 1978-01-25 | Ibm | Manufacture of masks |
| EP0097764A1 (en) * | 1982-06-30 | 1984-01-11 | International Business Machines Corporation | X-ray lithographic mask |
| GB2148540A (en) * | 1983-09-26 | 1985-05-30 | Canon Kk | Lithographic mask |
| US4528071A (en) * | 1983-10-25 | 1985-07-09 | Siemens Aktiengesellschaft | Process for the production of masks having a metal carrier foil |
Also Published As
| Publication number | Publication date |
|---|---|
| KR900017098A (en) | 1990-11-15 |
| KR920010065B1 (en) | 1992-11-13 |
| GB8915049D0 (en) | 1989-08-23 |
| NL8901516A (en) | 1990-11-16 |
| JPH02296244A (en) | 1990-12-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |