JPS62145816A - Photoelectric image transferring apparatus - Google Patents

Abstract

PURPOSE:To improve the throughput (processing efficiency) of a photoelectric image transferring apparatus by heat cleaning a semiconductor substrate surface when covering with a substance film for assisting photoelectron emitting amount, and then cooling the substrate in inert gas or neutral gas. CONSTITUTION:A GaAs substrate 1 is contained in a subchamber 3, an infrared light is emitted from a heating light source 31 to the substrate to heat the substrate to 650-680 deg.C, thereby evaporating to scatter moisture, GaAs oxide film and contaminated Cs film on the surface. Since the substrate 1 is heated to 650-680 deg.C, helium gas is gradually fed to the subchamber 3 to cool it by the convection of the gas. When it is heated to approx. 200-300 deg.C, the gas is blown to the substrate by regulating the position of a gas input tube 32 to rapidly cool it. When it is cooled to approx. 100 deg.C evacuating is started to high vacuum. The vacuum degree of the subchamber 3 is controlled to several Torr even during these operations so that the gas pressure may not considerably rise.

Description

[Detailed Description of the Invention] [Summary] In a photoelectronic image transfer device that uses a semiconductor substrate provided with a metal pattern as a mask and transfers a photoelectron image from the substrate mask, when coating a material film that enhances the amount of photoelectron emission. First, heat cleaning the semiconductor substrate surface, and then
The semiconductor substrate is configured to be cooled in an inert gas or neutral gas. In this way, throughput (processing efficiency) is improved.

FIELD OF INDUSTRIAL APPLICATION This invention relates to improvements in optoelectronic image transfer devices, ie, devices for transferring photoelectronic images from masks with photoelectronically active surfaces in lithographic technology.

As is well known, lithography technology has become particularly important when manufacturing semiconductor devices such as ICs.

Ultraviolet exposure has long been used as a lithography technique, and since then various improvements have been made to make it compatible with finer patterns, but due to the limitations of the light wavelength (approximately 4,000 at most), it is not suitable for submicron-level microfabrication. As it has been found to be suitable, methods such as electron beam exposure have come to be used frequently. However, the electron beam exposure method requires beam scanning and requires a long processing time, making it difficult to achieve high throughput. For this reason, shaped beam methods such as a variable rectangular beam have been developed in the electron beam exposure method, but these also have the drawback of being restricted by pattern shapes.

On the other hand, an X-ray exposure method has been developed, but it is impossible to reduce or form an image, and it is also difficult to create lenses.

Ion beam exposure methods are also being considered, but they similarly have drawbacks such as difficulty in producing lenses.

Therefore, it can be said that the mass-produced microfabrication exposure method has not yet been developed except for ultraviolet exposure, and research is still being carried out. Under these circumstances, the inventors developed a photoelectronic image transfer method for 1-size pattern transfer using a GaAs substrate mask coated with a Cs film etc.
9-243342, etc.).

According to this method, like the ultraviolet exposure method, it is possible to transfer a mask with a pattern all at once, and it is possible to mass-produce and achieve a high throughput. However, the transfer mask used in this photoelectronic image transfer device takes time to activate, and there is a desire to shorten the activation time.

[Prior Art] FIG. 2 shows a schematic sectional view of a conventional photoelectronic image transfer device, in which a desired W film with a film thickness of about 500 layers is deposited on a GaAs substrate 1.
A pattern 2 is provided, and a mask made of such a GaAs substrate 1 is housed in a subchamber 3 (pretreatment chamber) which is kept in a high vacuum. An ion beam device 30 is built in the subchamber 3, and the ion beam device irradiates an alkali metal Cs ion beam 5 from a Cs source (cesium source) 4 to the Cs photoelectronically active film M of several atomic layers. G of
It is formed on an aAs substrate 1. 6 in the figure is an extraction electrode, 7
is an electrostatic deflection electrode.

The GaAs substrate 1 mask treated in this way is transferred to the main chamber 10 (main processing chamber), and the W pattern 2 and the Cs
A wafer 11 to be exposed is placed at a position facing the mask surface on which the photoelectronically active film is formed. Then, for example, halogen lamp light 12 is irradiated onto the substrate surface, photoelectrons 13 are generated from the substrate surface, and the photoelectron image is transferred onto the wafer 11 surface. In this example, the light 12 is generated by a light source 14, reflected by a mirror 15, and irradiated onto the substrate surface. In addition,
In order to generate photoelectrons, a voltage of about -80 KV is applied to the substrate side, and in order to focus the photoelectrons on the wafer 11 surface with high precision, the substrate side is connected to the N pole 16. A uniform magnetic field is applied with the S pole 17 on the wafer side.

Further, 20 is a subchamber for storing wafers after transfer processing, and the processed wafers 11 are separated into chambers 2L by type.
It is stored in 22.

In this way, the W pattern 2 on the GaAs substrate 1 can be transferred to the resist film (not shown) on the wafer 11 at the same magnification. That is, since the amount of photoelectrons emitted from the PT pattern 2 with a large work function is small, and the amount of photoelectrons emitted from one surface of the GaAs substrate with a small work function and high quantum efficiency is large, the W pattern image is printed on the resist film surface of the wafer at the same magnification. The Cs photoelectronically active film M is used to enhance the amount of photoelectron emission. This auxiliary film is not limited to the Cs film, but may also be made of alkali metals or alkaline earth metals.

[Problems to be Solved by the Invention] However, when the Cs photoelectronically active film is repeatedly used, the resist film evaporates and material atoms in vacuum adhere to the Cs photoelectronically active film, causing photoelectron emission. The amount will start to decrease.

Therefore, when the amount of photoelectron emission decreases, the main chamber 10 is returned to the subchamber 3 again for activation processing. The method is to return the GaAs substrate 1 mask to the subchamber 3, heat it to a temperature of 650 to 680°C (the heated part is not shown in Figure 2), and remove the contaminated carbon.
The S film and other oxide films on the substrate surface are evaporated and scattered. Next, a Cs ion beam 5 is irradiated from the Cs source 4 of the ion beam device to deposit a new Cs photoelectronically active film on the surface again.

This activation process is the same when first coating the Cs photoelectronically active film. After heating the substrate mask in the subchamber 3 to evaporate and scatter the oxide film on the substrate surface, the Cs photoelectronically active film is applied to the surface. It is covered.

However, the so-called heat cleaning method, in which impurities are evaporated and scattered by heating to a temperature of 650 to 680 DEG C., has the drawback that the processing time is extremely long and the throughput is reduced. This is because when the heating temperature is raised to 650-680°C, the inside of the chamber is in a high vacuum of 10-6 Torr or more, so it is difficult to dissipate the heat, and it takes a considerable amount of time, for example, about 2 hours, to cool down to room temperature. are doing. On the other hand, if the GaAs substrate 1 used as a mask is not cooled to room temperature, a fine pattern with dimensional errors will be transferred due to the influence of thermal expansion of the substrate. For example, GaA
For the s-substrate, a temperature change of 1° C. causes an error of 0.06 μm/10 mm. Therefore, it is necessary to cool it to room temperature, which means that high throughput cannot be obtained.

The present invention proposes a photoelectronic image transfer device that solves the problem of lowering throughput.

[Means for solving the problem] The purpose is to heat the semiconductor substrate in the activation process to evaporate and scatter impurities on the surface, and then heat the semiconductor substrate in an inert gas or neutral gas. This is achieved by a photoelectronic image transfer device provided with an inert gas or neutral gas introduction structure for cooling.

[Function] That is, the present invention is configured to heat-clean the surface of a semiconductor substrate in a subchamber, and then cool the semiconductor substrate in an inert gas or neutral gas.

By doing so, the cooling time after the activation process can be shortened, and throughput can be improved.

[Example code] Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 1 shows a schematic sectional view of a photoelectronic image transfer device according to the present invention, and the same members as those in the photoelectronic image transfer device of FIG. 2 are given the same symbols.

In the subchamber 3, a symbol 31 indicates a heating light source (for example, an infrared heater), and a symbol 32 indicates a gas introduction pipe. That is, in the apparatus according to the present invention, a gas introduction pipe 32 whose position can be controlled is attached (the heating light source 31 is conventionally provided), and an inert gas such as lithium, neon, argon, etc. is attached to the gas introduction pipe 32. or a neutral gas such as nitrogen.

To explain an example of the operation, first C is placed on the GaAs substrate 1.
When coating s11M or when the amount of photoelectron emission from the GaAs substrate 1 decreases, Ga is added to the subchamber 3.
An As substrate 1 is housed, and the heating light source 31 irradiates the substrate with infrared light to heat the substrate to a temperature of 650 to 680° C., and evaporates and scatters moisture, GaAs oxide film, dirty Cs film, etc. on the surface. .

Then, since the GaAs substrate 1 is heated to 650 to 680[deg.] C., helium gas is gradually introduced into the subchamber 3 to cool it using gas convection. The reason why the gas is gradually introduced is to prevent sudden cooling and distortion of the substrate.

When the substrate is cooled to about 200 to 300° C., the position of the gas introduction pipe 32 is adjusted so that gas is blown onto the substrate surface, thereby cooling the substrate quickly. Then, when the temperature reaches about 100°C, suction to a high vacuum is started.

Even during these operations, the degree of vacuum in the subchamber 3 remains at several To
The gas pressure is controlled to about rr so that the gas pressure does not become too high. Thermal convection (heat radiation) due to the introduced gas is approximately 0.2 to 0.3
Since this occurs at Torr, cooling is performed at a degree of vacuum close to that limit.

The above is an example of a cooling operation, and when gas is introduced in this way, cooling can be achieved in about 30 minutes. Note that, as described above, it is desirable that the gas introduction pipe 32 be configured to be movable and whose position can be controlled.

After that, Cs is supplied from the Cs source 4 of the ion beam device 30.
Ion beam 5 is irradiated to deposit a new Cs photoelectronically active film M on the surface. This makes it possible to speed up the substrate activation process and improve throughput.

Note that in the subchamber 3 shown in FIG. 1, the ion beam device 30 is provided on the side, but this is for convenience of explanation; in reality, the heating light source 31 and the heating light source 31 are provided in the vertical direction of the main chamber 10. Preferably, the ion beam devices 30 are arranged in parallel.

[Effects of the Invention] As is clear from the above description, according to the present invention, the activation process of the substrate mask can be shortened and a high throughput can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a photoelectronic image transfer device according to the present invention, and FIG. 2 is a schematic sectional view of a conventional photoelectronic image transfer device. In the figure, 1 is a GaAs substrate, 2 is a PT pattern, M is a Cs photoelectronic active film, 3 is a subchamber (pretreatment chamber), 10 is a main chamber, 1 is a wafer, 12 is a halogen lamp light, 13 is a photoelectronic , 14 is a light source,
15 is a mirror, 16 and 17 are magnetic poles, 20 is a subchamber after transfer processing, 30 is an ion beam device,

Claims (1)

[Claims] A metal film pattern is provided on a semiconductor substrate, the semiconductor substrate including the metal film pattern is coated with a material film that lowers the work function, and using the semiconductor substrate as a mask, light is irradiated onto the semiconductor substrate surface to create an electric field. and a photoelectronic image transfer device that projects photoelectrons emitted from the semiconductor substrate surface by applying a magnetic field and transfers an image of the photoelectrons, the semiconductor substrate surface being heated in the activation process of the semiconductor substrate. In order to evaporate impurities on the surface and then cool the semiconductor substrate in an inert gas or a neutral gas, an inert gas or neutral gas introduction structure is provided. Photoelectronic image transfer device.