JPH056335B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a pattern forming method and apparatus for forming a pattern on a semiconductor element or a mask.

[Prior art]

Conventionally, known methods for forming patterns on a substrate include a deposition method, a sputtering method, a plasma CVD method, and an ion beam deposition method. However, these methods deposit a substance over the entire surface of the substrate, and are not suitable for deposition only on a localized portion of the substrate, for example, a minute portion with a diameter of 1 μm or less.

According to the laser CVD method, it is possible to deposit onto minute parts with a diameter of about 1 μm, but
Since the CVD method generally uses toxic gas, it is necessary to pay attention to safety measures, and the disadvantage is that the equipment is complicated and expensive. In addition, the minimum diameter of the deposited film is determined by the laser focusing spot diameter and the spread of heat generated by laser irradiation, with a diameter of 1 μm.
The extent is the limit.

[Purpose of the invention]

The present invention was made in view of the above-mentioned drawbacks of the prior art.
It is an object of the present invention to provide a pattern forming method and apparatus that can form the following microscopic deposition films and fine line patterns with a width of 1 μm or less.

[Summary of the invention]

The first pattern forming method of the present invention is to form a film of a substance on a substrate, and then irradiate the substrate with a focused ion beam in a vacuum to partially transform the material. The method is characterized in that the substrate is etched so as to leave the ion irradiated area to form a micro-transformed film on the substrate. A second pattern forming method of the present invention involves forming a film of a substance on a substrate, and then scanning and irradiating the substrate with a focused ion beam in a vacuum to partially transform the substance. The method is characterized in that the substrate is etched so as to leave the transformed ion irradiated area to form a metamorphic pattern film of a predetermined width on the substrate.
Further, the pattern forming method of the present invention includes: a film forming means for forming a film of a predetermined substance on a substrate; an ion beam irradiation means for irradiating the substrate with a focused ion beam to partially transform the substance; The present invention is characterized by comprising quadrupole mass spectrometry means for measuring the film thickness of a substance formed on the substrate.

The principle of the present invention is to mix incident ions and atoms of the irradiated substance by irradiation with an ion beam, and to transform the structure only in the ion irradiated area.

At this time, by using a recently invented liquid metal ion source or cryogenic FI ion source, a diameter of 1μ
The ion beam is focused on a spot of less than m in size, making it possible to form microscopic depositions and narrow patterns.

The above principle will be explained using the attached FIGS. 1 to 3. Here, it is assumed that the substance to be deposited has already been deposited on the substrate. As shown in FIG. 1, when ions 1 are irradiated, they collide with atoms 2 of the vapor deposited material and knock out the atoms 2 from their positions. If Ion 1 and Atom 2 still have enough energy to move through the material after the collision, they will cause another collision. Such collisions progress one after another, resulting in a phenomenon generally called cascade scattering. As a result, as shown in Figure 2, in the area irradiated with ion 1, the incident ion 1 and the atoms of the vapor deposited material 2
It becomes a mixed state. If the thickness of the vapor deposited film is appropriately selected, the mixed region reaches the substrate portion, where the incident ions 1, the atoms 2 of the vapor deposited substance, and the substrate atoms 3 are in a mixed state. For this reason, the adhesion of the film in that area is improved compared to other areas, and when the entire substrate is etched, only the ion irradiated area remains as shown in FIG. 3, allowing deposition on minute areas.
Further, by scanning the ion beam in a similar manner, it is possible to form a pattern with a minute width.

[Embodiments of the invention]

The present invention will be described in more detail below with reference to embodiments shown in the accompanying drawings.

FIG. 4 is a diagram showing a first embodiment of the pattern forming apparatus of the present invention. In the figure, the inside of the main chamber 4 is maintained at an ultra-high vacuum of 1×10 ⁻⁸ Torr. To introduce the sample 8 into this main chamber 4, close the valve 18 and close the valve 17.
is opened, the sample table 7 is carried into the subchamber (preliminary chamber for sample exchange) 16, and the valve 17 is closed.

Next, open the door of subchamber 16 and
Attach it to the sample stage 7. Then, after closing the valve 20 between the main pump 21 and the sub-pump 22, the valve 19 is opened to exhaust the inside of the sub-chamber 16. In this embodiment, subchamber 16
After evacuating the chamber to about 1×10 ⁻⁶ Torr, a deposition substance 10 is deposited to a constant thickness on the sample 8 using an electron beam impact heating type deposition device provided in the subchamber 16 . The configuration of this electron beam impact heating type vapor deposition apparatus is as follows. The vapor deposition material 10 is placed on a mesh 13 placed at the bottom of a ceramic holder 14. Further, the tungsten filament 11 and the electronic shield 12 are arranged as shown in the figure,
Applying current to the tungsten filament 11
Heat to over 1600℃. As a result, the tungsten filament 11 emits thermoelectrons 23.
Therefore, when a voltage of about 1 KV is applied between the tungsten filament 11 and the mesh 13 by the power source 15, the thermoelectrons 23 are attracted to the mesh 13, pass through the mesh 13, and collide with the vapor deposition material 10. As a result, the kinetic energy of the thermoelectrons 23 is converted into heat, and the vapor deposition material 10 is heated and evaporated. Atoms 24 of evaporated deposition substance 10
reaches the sample 8 on the sample stage 7 and is deposited on the sample 8.

The sample stage 7 carrying the sample 8 on which vapor deposition has been completed is introduced into the main chamber 4 by opening the valve 17. Next, close valves 17 and 19, and close valve 20.
Open 18 and 1x inside main chamber 4.
Exhaust to about 10 ^-8 Torr.

Next, the ion beam 9 extracted from the ion source 5 is focused and deflected by the ion optical system 6 and irradiated onto the sample 8.
Next, the thickness of the deposited film is measured using ion mass spectrometry. The ion beam 9 is irradiated onto an unnecessary part of the sample 8, and the secondary ions 2 emitted from the sample 8 are
5 is detected by the quadrupole mass spectrometer 26, and the result is output from the mass spectrometer controller 27. Sample 8
While the ion beam 9 is irradiating the upper deposited film, secondary ions ejected from the deposited film are detected. When the sputter etching progresses to the boundary between the sample 8 and the deposited film, secondary ions from both the sample 8 and the deposited film are ejected. Further, as the sputter etching progresses, the deposited film is completely removed from the irradiated area of the ion beam 9, so that only the secondary ions of the sample 8 are detected. For this reason, the vapor deposition material 10
When looking at the time change of the peak of the mass spectrum of sample 8, it becomes as shown in FIG. In FIG. 5, time to indicates the point at which sputter etching has progressed by the thickness of the deposited film. Therefore, if the time to is known from the sputter etching rate data of the vapor deposited material 10, the thickness of the vapor deposited film can be found. By knowing the thickness of the deposited film, the acceleration energy of the ion beam 9 can be set to a value suitable for depositing the deposited substance 10 on the sample 8 using the method described above.

Further, according to this embodiment, secondary ions from the sample 8 can be detected by irradiation with the ion beam 9.
Therefore, it corresponds to a scanning electron microscope and has the function of a scanning ion microscope. This function can be used to accurately set the deposition position.

FIG. 6 is a diagram showing a second embodiment of the pattern forming apparatus of the present invention. In this embodiment, the vapor deposition device 2
After vapor deposition atoms 30 are deposited in step 8 and ion beam 9 is irradiated thereon, vapor deposition atoms 31 are further deposited in vapor deposition device 29 . Therefore, in this embodiment, it is possible to form a microfilm as shown in FIG. FIG. 7a shows a state in which vapor-deposited atoms 30 are deposited on a sample 8, and an ion beam 9 is irradiated thereon to form a metamorphic layer 32. In FIG. 7b, another metamorphic layer 33 is formed by irradiating the ion beam 9 after further vapor depositing atoms 31. Thereafter, the deposited film other than the metamorphic layer 33 is removed by wet etching or dry etching using plasma.
It can be shaped as shown in Figure C. As a result, if the metamorphic layer 32 becomes a material that is susceptible to erosion from the outside world, such as oxidation, the metamorphic layer 32
to cover the metamorphic layer 32 and protect it from the outside world.
The lifespan of 2 can be extended. This embodiment also has a secondary ion mass spectrometry function and a scanning ion microscope function, and can perform film thickness monitoring and positioning.

Figure 8 is an enlarged view of a photomask for LSI manufacturing. FIG. 8a is a plan view of the photomask, and FIG. 8b is a sectional view. A pattern 34 is formed of chromium on a glass substrate 35. The photomask has black spot defects 36 where chromium is present in areas where there is no pattern due to manufacturing errors, etc.
A white spot defect 37, which is an omission in the pattern, has occurred. When these defects are transferred to LSIs, the yield of LSIs is significantly reduced, so these defects must be corrected. The black spot defect 36 can be removed by ion sputtering, but the white spot defect 3
7 could only be corrected up to about 1 μm using conventional laser beam correction. However, using the present invention, it has become possible to correct even white spot defects with a diameter of about 0.5 μm.

This time, we deposited zinc to a thickness of 500 Å, which has weaker adhesion to glass than chromium and has a relatively low melting point of 419.5°C, and focused a Ga ion beam onto the white spot defect 37 to a beam diameter of 0.1 μm at 20 KV. After irradiation,
When cleaning with ozone sulfuric acid, a film was formed only on the white spot defect 37, and the white spot defect 37 with a diameter of 0.5 μm could be repaired.

Correction of white spot defects is also possible in the first embodiment shown in FIG. This is because even if zinc is deposited on the entire surface of the photomask, unevenness remains on the photomask, and the surface of the photomask can be observed using the scanning ion microscope function. However, since the contrast deteriorated and the scanning ion microscope image became difficult to see, the white spot defect was corrected in the second embodiment shown in FIG. In the device shown in the second embodiment,
Before depositing zinc, the photomask is observed using a scanning ion microscope, and black spot defects are first removed by sputter etching. Next, using a scanning ion microscope, the axis of the ion beam 9 is aligned to the position of a white spot defect, which exists in about one photomask.
Zinc was then deposited to correct the white spot defects.

In addition, the following experimental results were obtained. In other words, the diameter is 0.1 μm on a sample with 1000 Å of As deposited on a Si substrate.
A focused Ga ion beam was scanned in a specific pattern. When the sample was plasma etched under appropriate conditions, a pattern made of a mixture of As and Ga was formed. Therefore, as a result of scanning the pattern with a laser beam and performing annealing,
It was confirmed that it exhibits electrical properties as a GaAs compound. In this experiment, since it was sufficient to deposit As on the entire surface of the substrate, pattern formation was performed using the apparatus of the first embodiment shown in FIG.

Currently, the ion sources that can produce ion beams that can be focused on a microscopic spot are cryogenic FI ion sources and liquid metal ion sources. The ions obtained by the cryogenic FI ion source are gas ions. Furthermore, only specific ion species can be obtained using liquid metal ion sources. Although progress is being made in the development of ion sources that extract B, As, Sb, etc., which are important dopant ions in semiconductor processes, a stable and long-life ion source that can be used in production lines has not yet been developed. Therefore, using the present invention, the material to be implanted was deposited on a substrate, and the material was irradiated with a narrow ion beam extracted from a cryogenic FI ion source with high acceleration energy of 50 KV or more. As a result, it was possible to implant B, As, and Sb to a depth of about 100 Å, although the beam spread to several times the diameter of the incident ion beam due to cascade scattering inside the substrate. The ions to be irradiated include Ne, Kr, etc., which have a large mass number, and the spread of the implanted materials in the lateral direction is small, and they are implanted deeply, resulting in good results.

〔Effect of the invention〕

According to the present invention, the diameter
Deposition and width of micro spots of 1μm or less
It has the effect of forming fine distribution patterns of 1 μm or less in fewer steps.

In addition, it is possible to deposit materials with high melting points and high vapor content that are difficult to extract, and by increasing the acceleration voltage of the ion beam to be irradiated, the material deposited on the substrate can be implanted into the substrate. can. The implantation depth and lateral spread at this time can be controlled by changing the ion accelerating voltage, scanning the beam, and blurring the focus.

[Brief explanation of the drawing]

1, 2, and 3 are explanatory diagrams showing the principle of the present invention, FIG. 4 is a diagram showing the first embodiment of the pattern forming apparatus of the present invention, and FIG. 5 is a diagram showing changes in mass spectrum peaks. FIG. 6 is a diagram showing a second embodiment of the pattern forming apparatus of the present invention, and FIGS. 7a, b, and c show the state of deposition using the second embodiment shown in FIG. 6. Explanatory drawings, Figure 8 a and b are
FIG. 3 is an explanatory diagram showing defects in a photomask for LSI. 1...Ion, 2...Atom of vapor deposited substance, 3...
Atoms of substrate, 4... Main chamber, 5... Ion source, 6... Ion optical system, 7... Sample stage, 8
... Sample, 9 ... Ion beam, 10 ... Vapor deposition substance, 11 ... Tungsten filament, 12 ...
...Electronic shield, 13...Mesh, 14...Ceramic holder, 15...Power source, 16...Subchamber, 17, 18, 19, 20...Valve, 21...Main pump, 22...Sub pump, 23... Thermal electron, 24...Atom of vapor deposited substance,
25... Secondary ion, 26... Quadrupole mass spectrometer, 27... Mass spectrometer controller, 28,2
9... Vapor deposition apparatus, 30, 31... Vapor deposition atoms, 3
1, 32... Metamorphic layer, 34... Pattern, 35...
...Glass substrate, 36...Black dot defect, 37...White dot defect.

Claims (1)

[Claims] 1. A substance is formed into a film on a substrate, and then a focused ion beam is irradiated onto the substrate in a vacuum to partially transform the material, and the irradiated area with the transformed ions is A pattern forming method characterized in that the substrate is etched so as to leave a micro-transformed film on the substrate. 2. A substance is formed into a film on a substrate, and then a focused ion beam is scanned and irradiated onto the substrate in a vacuum to partially transform the material, leaving behind the irradiated area with the transformed ions. A method for forming a pattern, comprising etching the substrate to form a metamorphic pattern film of a predetermined width on the substrate. 3 a film forming means for forming a film of a predetermined substance on the substrate;
ion beam irradiation means for irradiating the substrate with a focused ion beam to partially transform the substance; and quadrupole mass spectrometry means for measuring the film thickness of the substance formed on the substrate. A pattern forming device characterized by: 4. The pattern forming apparatus according to claim 3, wherein the film forming means and the ion beam irradiation means are provided in different chambers. 5. The pattern forming apparatus according to claim 3, wherein a plurality of the film forming means are formed to form films of different substances.