JPS62145815A - Photoelectric image transferring apparatus - Google Patents

Abstract

PURPOSE:To improve the quality of a substrate mask by heat cleaning a semiconductor substrate surface when activating the substrate mask, and measuring the temperature of the substrate from its back surface through an infrared ray transmission window by an infrared sensor at that time to control the temperature. CONSTITUTION:Three infrared sensors S1-S3 are provided, the mean value or weighted mean value of the measured temperatures is detected by a temperature control system 32, thereby controlling the heating amount of a heating light source 31. When the heating temperature of a semiconductor substrate 1 is measured from the back surface of the substrate, it has an advantage that steady and average temperature can be measured without influence of the pattern density of the surface. GaAs of several atom layers is evaporated and scattered simultaneously with an impurity in the heat cleaning step to expose a clean GaAs substrate surface. Thereafter, Cs ion beam 5 is emitted from a Cs source 4 of an ion beam unit 30 in the same subchamber 3 to cover the substrate surface with a new Cs photoelectron active film M. Thus, a substrate mask which has good photoelectron emission efficiency is formed, and when it is transferred in a main chamber 10, the pattern accuracy of a wafer 11 is further improved.

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 the substrate mask is activated, the semiconductor substrate surface is During heat cleaning, the temperature of the semiconductor substrate is measured by an infrared sensor from the back side through an infrared transmitting window to control the temperature. This improves the quality of the substrate mask.

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 lithography technology.

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

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.
No. 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, there is a demand for improvement in the activation process of the substrate mask used in this photoelectronic image transfer device, which emits a large amount of photoelectrons.

[Prior Art] FIG. 2 shows a schematic cross-sectional view of a conventional photoelectronic image transfer device. Sub-chamber 3 (pre-processing chamber) where the mask consisting of 1 is placed under high vacuum
to be accommodated. An ion beam device 30 is installed in the subchamber 3.
is built-in, and its ion beam device allows Cs
A Cs ion beam 5 of an alkali metal is irradiated from a source (cesium source) 4 to form a Cs photoelectronically active film M of several atomic layers on the GaAs substrate 1 described above. 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 5, 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 wafer side as the south pole F.

Further, 20 is a sub-chamber that accommodates wafers after the transfer process, and the processed wafers 11 are stored in the chamber 21 by type.
．． It is stored in 22.

In this way, the PT pattern 2 on the GaAs substrate 1 can be transferred to the resist film (not shown) on the wafer 11 at the same size. That is, since the amount of photoelectrons emitted from the W 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, in a so-called heat cleaning process in which the substrate mask is heated to evaporate and scatter impurities such as water, oxides, and a dirty Cs film, temperature control at a temperature of 650 to 680° C. is extremely important.

That is, when the substrate heating temperature is lower than 650℃, GaAs
It is not possible to evaporate and scatter the oxide film of 680
When the temperature is higher than ℃, ^S starts to evaporate, so in order to expose a clean GaAs substrate with good quantum efficiency,
It is necessary to properly control the substrate temperature to the temperature at which the GaAs substrate evaporates in the GaAs compound state, that is, the above-mentioned 650 to 680° C., and cleaning at that temperature provides the best amount of photoelectron emission.

The present invention proposes a photoelectronic image transfer apparatus in which the heating temperature of the substrate mask can be accurately controlled to the above-mentioned temperature in the heat cleaning step of such activation treatment.

[Means for solving the problem] The purpose is to control the temperature of the semiconductor substrate by measuring it with an infrared sensor from the back side of the semiconductor substrate through an infrared transmission window during activation processing of the semiconductor substrate. This is accomplished by a photoelectronic image transfer device configured.

[Operation] That is, in the present invention, for example, in a subchamber, a semiconductor substrate surface is heat-cleaned, and at that time, the temperature of the semiconductor substrate is measured and controlled by an infrared sensor from the back surface of the substrate through an infrared transmission window.

Then, the semiconductor substrate with the best photoelectron emission amount (
mask) is obtained.

[Example] 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 and its vicinity, symbol 31 is heating light m<for example, an infrared heater), 32 is a heating temperature control system, and symbol 3 is an infrared transmission window, Sl, 52. S3 each indicates an infrared sensor. That is, in order to perform heat cleaning within the subchamber 3, a measurement controller using an infrared sensor is attached to the chamber.

Since three infrared sensors are provided in this example, the average value or weighted average value of the measured temperatures is detected by the temperature control system 32, and the heating amount of the heating light source 31 is controlled accordingly. Such a temperature control system 32 uses a known electronic circuit. In addition, the infrared sensors Sl, S2゜S3, for example,
A CdTe infrared detection element is used and placed close to an infrared transmission window. The infrared transmitting window 3- is made of, for example, a germanium crystal plate. The germanium crystal plate has good infrared transmittance, and can be hermetically sealed to maintain a high vacuum inside the subchamber 3.

With this configuration, when the heating temperature of the semiconductor substrate I is measured from the back surface of the substrate, there is an advantage that a steady and average temperature can be measured without being influenced by the pattern density on the front surface. Thus, by the heat cleaning process,
Several atomic layers of GaAs are evaporated and scattered at the same time as the impurities, and a clean GaAs substrate surface is exposed.

After that, in the same subchamber 3, a Cs ion beam 5 is irradiated from the Cs source 4 of the ion beam device 30 to deposit a new Cs photoelectronically active film M on the substrate surface. In this way, a substrate mask with high photoelectron emission efficiency is created, and when the transfer process is performed using the mask in the main chamber 10, the pattern accuracy of the wafer 11 is further improved.

Note that in the subchamber 3 shown in FIG. Preferably, the devices 30 are arranged in parallel.

[Effects of the Invention] As is clear from the above description, according to the present invention, a substrate mask with the best photoelectron emission amount can be created, the exposure contrast can be improved, and the transferred pattern can be of even higher quality. It is something that can be converted into

[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, 11 is a wafer, 12 is a halogen lamp light, 13 is a photoelectronic film, 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, 31 is a heating light source, 32 is a heating temperature control system, Mouse is an infrared transmission window, 31, S2. S3 indicates an infrared sensor.

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 surface of the semiconductor substrate by applying a magnetic field and transfers an image of the photoelectrons, the temperature of the semiconductor substrate being controlled by the temperature during activation processing of the semiconductor substrate. A photoelectronic image transfer device characterized in that the temperature can be controlled by measuring with an infrared sensor through an infrared transmitting window from the back side of a semiconductor substrate.