JP2785190B2 - Pattern forming equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming apparatus, and is particularly suitable for forming a pattern having an extremely fine width.

[Summary of the Invention]

The pattern forming apparatus according to the present invention includes a direct drawing apparatus by irradiating a charged particle beam in an atmosphere containing a source gas, a dry pump for evacuating the inside of the direct drawing apparatus, the direct drawing apparatus and the dry pump. A spring constant of the connection portion is k, a diameter of the charged particle beam is d, a mass of the direct writing device is m, and an angular frequency of vibration of the direct writing device is ω. When the amplitude of the vibration of the dry pump is A It is. As a result, a pattern having an extremely fine width can be formed with high accuracy and in one process.

[Conventional technology]

Conventionally, as a technique for forming a resist pattern, photolithography using light and electron beam lithography using an electron beam have been used. In these photolithography and electron beam lithography, five steps of resist coating, baking, exposure, development, and post-baking are required, and a wet process is used.

[Problems to be solved by the invention]

In the above-described photolithography, it is impossible to obtain a resolution lower than the wavelength of light used for exposure, so that the minimum pattern width that can be formed is limited to about 0.25 μm. In addition, instead of light, X-rays using short X-rays having a wavelength of several
Line lithography is also known, but in this case, a light source requires a large-scale apparatus such as a synchrotron orbital radiation (SOR) apparatus, and the configuration of an optical system such as a lens and a mask is generally difficult. There is a problem.

On the other hand, electron beam lithography has a high resolution inherent in the electron beam, but when the electron beam irradiates the resist, multiple scattering of electrons occurs in the resist, which lowers the resolution. The minimum possible pattern width is about 0.1 μm.

An object of the present invention is to provide a pattern forming apparatus which can form a pattern having an extremely fine width with high precision based on a dry process.

Another object of the present invention is to provide a pattern forming apparatus capable of forming a pattern having an extremely fine width in one process.

[Means for solving the problem]

In order to solve the above-mentioned problems, a pattern forming apparatus according to the present invention includes a direct writing apparatus (1) by irradiation of a charged particle beam (11) in an atmosphere containing a source gas, and an evacuation of the inside of the direct writing apparatus (1). Dry pump for cleaning (16)
And a connecting portion (15) for connecting the direct drawing apparatus (1) and the dry pump (16), wherein the spring constant of the connecting portion (15) is k, the diameter of the charged particle beam (11) is d, When the mass of the direct drawing apparatus (1) is m, the angular frequency of vibration of the direct drawing apparatus (1) is ω, and the amplitude of vibration of the dry pump (16) is A It is.

The connecting portion (15) constitutes a conduit for evacuating the inside of the direct writing apparatus (1).

As the charged particle beam (11), a positron beam, a muon beam, or the like can be used in addition to the electron beam. When an electron beam is used, it is preferable to use a field emission gun capable of generating an electron beam having good coherence.

As the dry pump (16), a turbo molecular pump, a cryopump, or the like can be used.

[Action]

Consider the vibration of the direct drawing apparatus (1) using a dry pump (16) for evacuating the inside of the direct drawing apparatus (1) as a vibration source. In this case, the spring constant k of the connecting portion (15) connecting the direct drawing device (1) and the dry pump (16) is set.
Is selected so as to satisfy the expression (1), the vibration of the direct drawing apparatus (1) caused by the vibration of the dry pump (16) can be greatly reduced. Hereinafter, the reason will be described.

The equation of the forced vibration of the direct drawing apparatus (1) using the dry pump (16) as a vibration source is expressed by the direct drawing apparatus (1)
When the horizontal displacement from the equilibrium position of x is x, m = −k (x−Ae ^iωt ) (2) Here, t indicates time, and A indicates the amplitude of forced vibration by the dry pump (16). X = Be in equation (2)
^Aiomegati (B direct amplitude of the vibration of the drawing device (1)) becomes putting the ^{-mBω 2 e iωt = -k (Be} iωt -Ae iωt) ...... (3). When the equation (3) is rearranged, mBω ² −kB = −kA (4) Than this It is.

The condition for performing drawing with the charged particle beam (11) with dimensional accuracy equal to or less than the beam diameter d is Bd. In this case, from equation (5) Becomes Here, (m / k) ω ² >> 1 is considered, and (m / k) ω
^If 1 is ignored for ² , the condition of equation (6) becomes Becomes By transforming equation (7), equation (1) is derived.

As described above, according to the means described above, the connecting portion (15)
Is selected so as to satisfy the expression (1), the vibration of the direct drawing apparatus (1) can be greatly reduced. Thus, the fluctuation of the charged particle beam (11) due to the vibration of the dry pump (16) can be extremely reduced, and therefore, the direct writing with the charged particle beam (11) can be performed with high accuracy. Moreover, since the diameter d of the charged particle beam (11) can be made extremely small, a pattern (24) having an extremely fine width can be formed. Further, the pattern (24) can be formed in one step of direct drawing by the charged particle beam (11).

[Example]

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. This embodiment shows an embodiment in which the present invention is applied to a pattern forming apparatus using direct writing by an electron beam.

FIG. 1 shows a pattern forming apparatus according to one embodiment of the present invention.

As shown in FIG. 1, the pattern forming apparatus according to this embodiment has a direct writing apparatus 1 using an electron beam having the same configuration as a scanning electron microscope (SEM). The direct writing apparatus 1 has a lens barrel 2 and a sample chamber 3. In the lens barrel 2, a field emission electron gun 4, a focusing lens 5, and a deflecting lens 6 capable of generating an electron beam having good coherence are provided. The deflection lens 6 is controlled by an electron beam controller 7.

On the other hand, a sample stage 8 is provided in the sample chamber 3, and a substrate 9 is arranged on the sample stage 8. This sample table 8
For example, the substrate 9 can be heated or cooled by a temperature controller 10 composed of a resistance heater and a Peltier cooler (cooler using the Peltier effect), whereby the substrate 9 can be set to a predetermined temperature. I have. The electron beam generated by the field emission electron gun 4
After the electron beam 11 is focused by the focusing lens 5, the focused electron beam 11 is deflected by the deflection lens 6 controlled by the electron beam controller 7, and scans the substrate 9 placed on the sample stage 8. It has become.

Reference numeral 12 denotes a container in which a resist material is stored. Then, the resist raw material in the container 12 can be introduced into the sample chamber 3 through the conduit 13. As the resist raw material, for example, alkyl naphthalene can be used. Reference numeral 14 denotes a mass flow controller for adjusting the flow rate of the resist raw material. The above-mentioned alkyl naphthalene is liquid at room temperature,
It is easily gasified in the sample chamber 3 kept in a vacuum.

In this embodiment, the evacuation of the sample chamber 3 is performed by a turbo-molecular pump 16 connected to the sample chamber 3 via a flexible tube 15 having a large diameter and a sufficiently high conductance. A rotary pump 17 is connected to the exhaust side of the turbo molecular pump 16. Also,
The turbo-molecular pump 16 is covered with a shield 18 for shielding a magnetic field generated from a motor for driving the turbo-molecular pump 16. As a material of the shield 18, for example, a magnetic material such as permalloy is used. Similarly, the vacuum evacuation of the lens barrel 2 is performed by a turbo-molecular pump 20 connected to the upper part of the lens barrel 11 via a flexible tube 19. Reference numeral 21 indicates a rotary pump connected to the exhaust side of the turbo-molecular pump 15, and reference numeral 22 indicates a shield for shielding a magnetic field generated from a motor for driving the turbo-molecular pump 20, similar to the shield 18. Is made of a magnetic material such as permalloy.

In this embodiment, the vibration of the direct drawing apparatus 1 using the turbo molecular pump 16 as a vibration source is the biggest cause of lowering the drawing accuracy by the electron beam 11, and therefore, the flexible tube 15 is used to prevent this. Spring constant k
Is selected to satisfy the expression (1). A specific calculation example of the spring constant k is shown below. Turbo molecular pump
The amplitude of vibration at the time of operation of No. 16, that is, A in equation (1)
Can be considered to be 1 μm = 10 ⁻⁶ m or less. Further, when the rotation speed of the turbo molecular pump 16 is, for example, 40,000 rpm, ω = 2π × (40000/60) to 4 × 10 ³ rad / s. The mass m of the direct writing apparatus is, for example, about 100 kg. Also,
Consider the case where the electron beam 11 is narrowed down most, and d = 10Å =
10 ^-9 m. Substituting these values into equation (1) Becomes

Next, a method of forming a resist pattern by the pattern forming apparatus according to the present embodiment configured as described above will be described.

In FIG. 1, the sample chamber 3 is controlled by a turbo molecular pump 16.
While the inside is evacuated to a high vacuum (for example, about 3 × 10 ⁻⁷ Torr) in advance, the resist material in the container 12 is introduced into the sample chamber 3 through the conduit 13 while controlling the flow rate by the mass flow controller 14. The pressure of the resist raw material gas in the sample chamber 3 is set to a value within the range of 10 ^-7 to 10 ^-5 Torr, for example, about 10 ^-6 Torr. Here, the upper limit of the gas pressure is such that if the gas pressure becomes too high, the gas flows into the lens barrel 2 from the sample chamber 3 and the pressure near the field emission electron gun 4 becomes high. This is because the field emission electron gun 4 may be damaged. The lower limit of the pressure of this gas is to ensure a resist growth rate equal to or higher than a certain value, and since the ultimate pressure in the sample chamber 3 before the introduction of the source gas is about 10 ^-7 Torr, This is because there is no point in reducing the pressure. In the sample chamber 3, a substrate 9 such as a gallium arsenide (GaAs) substrate is previously arranged on a sample stage 8, and is maintained at a predetermined temperature by a temperature controller. Here, it is assumed that a metal film 23 such as a tungsten (W) film is formed on the substrate 9 as shown in FIG. 2A.

When the pressure of the resist raw material gas in the sample chamber 3 reaches a predetermined value, an electron beam 1 is generated by the field emission electron gun 4,
The electron beam 11 is scanned on the metal film 23 under the control of the electron beam controller 7 in the resist source gas atmosphere, and a predetermined pattern is drawn. In this case, the acceleration voltage of the electron beam 11 is set to a value within the range of 0.5 to 6 kV. The lower limit of the acceleration voltage comes from the difficulty in controlling the electron beam 11 when the acceleration voltage is 0.5 kV or less,
The upper limit comes from the fact that when the acceleration voltage is 6 kV or more, multiple scattering of electrons when the electron beam 11 is irradiated becomes remarkable. The beam current is set to a value within the range of 10 ^-13 to 10 ^-7 A. The lower limit of the beam current comes from securing a resist growth rate of a certain value or more, and the upper limit comes from the performance of the field emission electron gun 4. The beam diameter of the electron beam 11 is, for example, about 100 °.

In the above-described resist source gas atmosphere, resist source gas molecules are adsorbed on the surface of the metal film 23. When the electron beam 11 is irradiated on the adsorbed resist material molecules,
The resist material molecules in the portion irradiated with the electron beam 11 are converted into hydrocarbons. As a result, a substance composed of hydrocarbons is generated on the metal film 23 in the same shape as the drawing pattern of the electron beam 11. Thus, a resist pattern 24 made of hydrocarbon is formed. The resist pattern 24 made of this hydrocarbon has excellent dry etching resistance. Since the thickness of the resist pattern 24 formed by one drawing with the electron beam 11 is usually small, the resist material molecules adsorbed on the once formed resist pattern 24 are irradiated with the electron beam 11 to form a hydrocarbon. This process is repeated to make the resist pattern 24 have a predetermined thickness. FIG. 2B shows this state. In this case, on the part of the metal film 23 where the electron beam 11 is not irradiated, when the adsorbed resist material molecules become several atomic layers, the adsorption of the resist atomic molecules is saturated, and further adsorption does not occur. Therefore, resist growth does not occur in portions where the electron beam 11 is not irradiated.

As shown in FIG. 2B, a resist pattern 24 having a predetermined thickness is formed.
Is formed, the metal film 23 is then subjected to, for example, reactive ion etching (RI
Perform anisotropic etching in the direction perpendicular to the substrate surface according to E). Thereby, as shown in FIG. 2C, a metal ultrafine line 25 having the same shape as the resist pattern 24 and a width of, for example, about 100 ° is formed. After this, the resist pattern
24 is removed by etching to obtain the state shown in FIG. 2D.

The metal ultrafine wire 25 can be used as a Schottky gate electrode of a Schottky gate FET such as a GaAs MESFET, a wiring, or the like. Using this metal trace thin wire 25 as a Schottky gate electrode, which can be extremely high ultrafast operation transconductance g _m
It is possible to realize FET.

As described above, according to this embodiment, the direct drawing apparatus 1
The spring constant k of the flexible tube 15 connecting the pump and the turbo-molecular pump 16 is selected so as to satisfy the expression (1). The vibration is very small. For this reason, blurring of the electron beam 11 is extremely small, and therefore direct writing with the electron beam 11 can be performed with high accuracy. Further, since the resist pattern 24 can be formed in one process of direct writing by the electron beam 11, the process required for forming the resist pattern 24 can be greatly reduced as compared with the related art.

Further, in this embodiment, since writing is performed using the electron beam 11 having good coherence generated by the field emission electron gun 4, the resist pattern 24 can be formed with a resolution of about several tens of millimeters. Thus, the metal ultrafine wire 25 can be formed as described above. More generally, for example, it is possible to form an ultrafine structure having a size smaller than the de Broglie wavelength (about several hundreds of square meters) of electrons in a semiconductor, so that it is possible to realize a device or the like utilizing the quantum effect. Becomes

Further, since the evacuation of the inside of the sample chamber 3 is performed by the oil-free turbo-molecular pump 16, the resist pattern 24 can be formed in a clean vacuum where no oil molecules exist.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible.

For example, in the above-described embodiment, the turbo molecular pump 1
It is also possible to connect a diffusion pump to the exhaust side of 6, 20. Further, for example, vacuum evacuation in the lens barrel 2 can be performed by, for example, an ion pump.

〔The invention's effect〕

As described above, according to the present invention, a pattern having an extremely fine width can be formed with high accuracy and in one process.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a pattern forming apparatus according to an embodiment of the present invention, and FIGS. 2A to 2D are diagrams for explaining a method of forming a resist pattern by the pattern forming apparatus shown in FIG. FIG. Explanation of main reference numerals in the drawings 1: direct drawing device, 2: barrel, 3: sample chamber, 4: field emission electron gun, 8: sample stage, 9: substrate, 11: electron beam, 15, 19: flexible tube , 16, 20: turbo molecular pump, 18, 22: shield, 24: resist pattern, 25: metal ultrafine wire.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-8479 (JP, A) JP-A-57-42127 (JP, A) JP-A-55-18084 (JP, A) JP-A 57-42 188787 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H01L 21/027 G03F 7/20 F04B 37/08

Claims (2)

(57) [Claims] 1. A direct drawing apparatus by irradiating a charged particle beam in an atmosphere containing a source gas, a dry pump for evacuating the inside of the direct drawing apparatus, and connecting the direct drawing apparatus and the dry pump. A connecting part, wherein the spring constant of the connecting part is k, the diameter of the charged particle beam is d, the mass of the direct drawing device is m, the angular frequency of vibration of the direct drawing device is ω, and the dry pump is When the amplitude of vibration of A is A A pattern forming apparatus, characterized in that: 2. The pattern forming apparatus according to claim 1, wherein said charged particle beam is an electron beam generated by a field emission electron gun.