JPH02137312A - Electron beam aligner - Google Patents

Abstract

PURPOSE:To extremely reduce the positional deviation of a lithography pattern at the initial and end of aligning by providing a hot plate in a sub chamber, and preheating a holder for holding a substrate. CONSTITUTION:A sub chamber 2 is adhered to the side of the main chamber 1 of an electron beam aligner, a hot plate 9 is provided in the chamber 2, a holder 4 holding a substrate 3 is previously heated to a predetermined temperature, and a lithography with an electron beam is then conducted. Accordingly, the influence of heat to the holder, i.e., the influence of heat generated at an electron beam barrel provided at the top of the chamber 1 can be reduced. Thus, it can prevent the position of a regulating reference mark for detecting the origin of the beam from deviating due to the thermal deformation of the holder while a long lithography time to cause the lithography pattern to deviate.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to an electron beam exposure apparatus, and an object of the present invention is to prevent pattern displacement due to thermal deformation of a holder that holds a substrate. The side wall of the main chamber, in which the XY stage is installed, and one side wall of the cylindrical sub-chamber are joined via a valve, through which the holder can freely pass and which connects the two chambers. The other side wall of the subchamber is provided with a valve that can be opened and closed to allow the holder to be taken in and taken out and to be airtightly isolated from the atmosphere. A hot plate for preheating a holder holding a substrate is installed in the subchamber, and for exposure, the holder is placed on the hot plate through the valve and preheated, and then It is configured such that it is placed on the XY stage through the bulb and exposed, and after exposure is taken out to the outside through the two bulbs.

[Industrial application field]

The present invention relates to an electron beam exposure apparatus.

In recent years, as electronic devices, mainly semiconductor integrated circuits, have become smaller and more highly integrated, pattern miniaturization has entered the submicron range.

Along with this, various microfabrication techniques for forming micropatterns are being actively developed.

Among various processing techniques for performing fine patterning, a patterning technique centered on photoetching, called photolithography, is currently in use.

One of the elemental technologies in patterning technology using photoetching is exposure technology.

Depending on the type of light source (ray source), exposure technologies include ultraviolet exposure, which has traditionally been the most common method used for transfer, and X-ray exposure, which is expected to become more popular in the future.
Since it is a charged particle beam, it can be deflected by an electromagnetic field, and can be classified into electron beam exposure using an electron beam as a light source, which is used not only for transfer but also for direct writing, and ion beam exposure using an ion beam as a light source.

Among these, electron beam exposure has the characteristic that data such as the position and shape of a pattern is processed by a computer and does not require a specific mask or reticle.

Also, the spot size of the electron beam is considerably less than 1 μm.

Therefore, it is also possible to perform recent submicron patterning by direct exposure, especially when using a reticle (magnification mask).
It is very powerful for drawing masks.

-1, in electron beam exposure, a drawing (exposure) method is used in which a collection (field) of fine patterns is drawn one after another.

Therefore, holding substrates such as wafers and mask dry plates,
In addition, a technology for mechanically and extremely precisely controlling an XY stage on which a holder with a reference mark for determining the origin of the electron beam is placed is essential.

In other words, the development of fine patterning technology using electron beam exposure equipment and the accompanying improvement in manufacturing yields depend largely on how accurately and reproducibly the XY stage on which the substrate is placed is controlled.

However, no matter how controllable the XY stage is (no matter how you move it,
Currently, the holder placed thereon is unavoidably deformed due to thermal expansion due to the influence of heat.

[Conventional technology]

FIG. 2 shows a configuration diagram of a substrate holding section in an electron beam exposure apparatus.

In the figure, the substrate holding section includes a holder 4 that holds the substrate 3, and an XY stage 5 that moves the holder 4 in either the X direction or the Y direction (both in one direction).

Further, the holder 4 is provided with an adjustment reference mark 10, and a fulcrum 11 of the board is set therein.

Here, in the case of direct exposure, the substrate 3 is, for example, a semiconductor wafer coated with an electron beam resist, and in the case of producing a mask, for example, a thin film of metallic chromium (Cr) or chromium oxide (CrzOz) is used. For example, an electron beam resist is applied to a glass dry plate with a layer attached to the surface.

The material of the holder 4 is titanium, a metal with a small coefficient of linear expansion, in order to reduce the physical effects of heat as much as possible.
Ti) or ceramics such as alumina (AIgo3) and silicon nitride (StJ4) are used.

As the adjustment reference mark 10, for example, a step such as a protrusion or groove may be used, or a Faraday cup may be used.

During writing, the position of the adjustment reference mark 10, that is, the origin of the electron beam, is monitored by the electron beam itself at appropriate time intervals, and adjustments are made to reduce positional deviations due to electron beam drift, etc. .

However, at present, although not shown in the drawings, the holder 4 is affected by heat generated within the lens barrel that generates the electron beam, which includes an electron gun, lens system, and deflection system, resulting in thermal expansion and contraction of the holder 4. Heat deformation is inevitable.

For example, if the room temperature is 23°C and the holder 4 receives heat from the lens barrel and its temperature rises to 30°C, then
There is a temperature difference of °C.

Under these conditions, the adjustment reference mark 10 and the fulcrum 1 of the board
If we perform a trial calculation for the case where the distance to 1 is set to 30 m, we will get the following results.

In other words, when titanium metal is used as the material of the holder 4, the coefficient of linear expansion is 9X10''/''C, so it is 1.98
This results in a positional deviation of μm.

In addition, in the case of silicon nitride, the coefficient of linear expansion is 1.9.
Since X10-'/''C, a positional deviation of 0.40 μm occurs.

This result shows that silicon nitride is far superior to metal titanium as a material for the holder 4.

However, even with ceramics such as silicon nitride, which have a small coefficient of linear expansion, the position of the pattern before and after a long exposure time of up to 2 hours may vary due to its specific heat and thermal conductivity properties. Misalignment, that is, misalignment between fields that causes disconnections between patterns, is
It becomes ±0.2 to 0.3 μm.

This means that the adjustment reference mark 10, which determines the position of the origin of the electron beam, moves by this amount with respect to the fulcrum 11 of the substrate due to thermal deformation of the holder 4.

[Problem to be solved by the invention]

As mentioned above, in the substrate holding part of an electron beam exposure apparatus, due to the influence of heat generated in the electron beam column,
Thermal deformation such as thermal expansion and contraction of the holder that holds the substrate is unavoidable.

For this reason, even if the holder is made of a material with a small coefficient of linear expansion, such as ceramic, the relative positional relationship between the adjustment reference mark that determines the position of the origin of the electron beam and the fulcrum of the substrate will shift. .

As a result, a positional shift occurs between the pattern drawn at the beginning of electron beam exposure, which requires a long time, and the pattern drawn in the middle or at the later stage, and the connections between fields are shifted.
There were problems such as disconnections between patterns.

Therefore, the problem is how to reduce positional deviations that occur in patterns that have been drawn by electron beam exposure.

[Means to solve the problem]

The above-mentioned problem can be solved by preheating the holder prior to exposure in order to prevent the holder holding the substrate from being thermally deformed in the main chamber of the electron beam exposure system. .

That is, the a-wall of the main chamber, in which the XY stage on which the holder holding the substrate is placed, is connected to one side wall of the cylindrical sub-chamber via a valve, and the valve is connected to the holder. The sub-chamber is provided with an openable and closable valve on the other side wall of the sub-chamber to allow the holder to pass therethrough and to airtightly isolate the two chambers from the atmosphere. A vacuum evacuation system is connected to the bottom opening, and a hot plate is installed inside the subchamber to preheat the holder holding the substrate. During exposure, the holder is attached to the other side wall of the subchamber. After preheating by placing it on a hot plate through a provided valve, it is placed on an XY stage and exposed through a valve provided on the partition wall from the main chamber. After exposure, it is taken out through two valves. This is achieved by an electron beam exposure apparatus configured as described above.

[For production]

As mentioned above, in the present invention, a subchamber is joined to the side of the main chamber of an electron beam exposure apparatus,
A hot plate is installed inside the subchamber,
A holder holding a substrate is heated to a predetermined temperature in advance, and then drawing is performed using an electron beam.

By doing so, it is possible to reduce the effect of heat on the holder, that is, the effect of heat generated in the electron beam column provided in the upper part of the main chamber.

In this way, the position of the adjustment reference mark for detecting the origin of the electron beam is prevented from shifting due to thermal deformation of the holder during a long drawing time, and as a result, the position of the drawn pattern is prevented from shifting. Can be done.

The process of preheating the holder before entering the exposure process is called temperature annealing.

As mentioned earlier, for example, silicon nitride,
Even if the holder is made of ceramic with a small coefficient of linear expansion, the holder will be thermally deformed due to its characteristics such as specific heat and thermal conductivity, and the adjustment reference mark provided on the holder to monitor the origin of the electron beam. causes misalignment.

However, this temperature annealing resulting in the present invention allows e.g.
The occurrence of pattern misalignment before and after a long exposure time of up to 2 hours can be reduced to within a practical range.

〔Example〕

An example will be described below with reference to an explanatory diagram of an example in FIG.

Inside the main chamber 1 is a holder 4 holding a substrate 3.
An XY stage 5 with 200 squares on each side was installed.

Although not shown, this XY stage 5 can be moved in the XY directions with an accuracy of ±0.02 μm using a servo drive system and a stage feedback mechanism.

A valve 6 through which the holder 4 holding the substrate 3 can pass was provided on the partition wall between the main chamber 1 and the subchamber 2 connected to the main chamber 1, and a door that was automatically opened and closed by pressurized nitrogen was provided.

Although not shown, the holder 4 can be moved in either direction by an electric mechanism that moves between the main chamber 1 and the subchamber 2 through the valve 6.

On the other hand, a valve 7 was provided on the other side wall of the subchamber 2 to allow the holder 4 holding the substrate 3 to be taken in and out of the subchamber 2 .

This valve 7 also opens and closes automatically using pressurized nitrogen.

Furthermore, a vacuum exhaust system 8 is connected to the bottom opening of the subchamber 2, so that the inside of the subchamber 2 is connected to the main chamber l.
The same vacuum atmosphere can be created.

As the substrate 3, a chromium glass dry plate for a reticle, which had a size of 5 inches square and was coated with an electron beam resist, was used.

The holder 4 was made of titanium metal.

First, the valve 6 was closed to isolate the main chamber 1 and the subchamber 2, and the main chamber 1 was brought to a predetermined degree of vacuum.

At the same time, the hot plate 9 in the subchamber 2
was prewarmed to 30.5"C.

This temperature corresponds to +0.1° C. of the temperature at which the holder 4 increases in temperature due to the influence of surrounding heat during exposure in the main chamber 1 of the electron beam exposure apparatus used here.

The holder 4 holding the chrome mask substrate 3 is attached to the valve 7.
It was placed on the hot plate 9 in the subchamber 2 through the tube.

The valve 7 is closed, and the subchamber 2 is removed by the evacuation system 8.
The holder 4 was preheated while increasing the degree of vacuum.

20 minutes after confirming with a thermocouple surface thermometer that the temperature of the holder 4 has risen to 30°C, open the valve 6.
The holder 4 holding the substrate 3 was moved to the main chamber 1, and the valve 6 was closed.

A JIS standard pattern was used as the pattern drawn with an electron beam, and drawing was performed for about 2 hours using a 5x reticle.

During this time, the origin of the electron beam was adjusted every 3 minutes by detecting the position of the adjustment reference mark 10.

After the exposure was completed, the holder 4 was transferred to the subchamber 2 through the valve 6 and then taken out to the outside through the valve 7.

The exposed dry plate was developed and etched according to a prescribed procedure to obtain a reticle.

As a result of measuring the pattern accuracy of the reticle thus obtained using a length measuring microscope, it was confirmed that a good effect was confirmed in which the positional deviation between the pattern at the early stage and the latter stage of exposure was within the range of ±0.1 μm.

The embodiment described above is a typical embodiment of the present invention, and the present invention is not limited thereto, and various modifications are possible.

That is, various modifications can be made to the method of horizontally installing the subchamber, the method of transferring the holder, and the like.

In addition, conditions such as the preheating temperature and preheating time of the hot plate are determined by the configuration and specifications of the electron beam exposure equipment itself, and how the holder placed on the stage is affected thermally. It is not a determined value.

〔Effect of the invention〕

As described above, according to the electron beam exposure apparatus according to the present invention, a hot plate is provided in the subchamber installed horizontally in the main chamber, and by preheating the holder that holds the substrate, , it is possible to prevent the holder from deforming due to the influence of heat.

This makes it possible to minimize the positional deviation of the drawn pattern between the early and late stages of exposure.
It greatly contributes to higher precision of patterns in electron beam exposure.

[Brief explanation of the drawing]

FIG. 1 is a detailed explanatory diagram of the present invention, Figure 2 is a configuration diagram of the substrate holder; It is. In the figure, 1 is the main chamber 3 is the board, 2 is a subchamber, 4 is a holder, 5 is the XY stage, 8 is the vacuum exhaust system, 10 is the adjustment reference mark, It is. 6.7 is a valve, 9 is a hot plate, 11 is the fulcrum of the board, Explanation diagram of the unseen case of June failure VJI diagram Figure 2

Claims (1)

[Claims] A side wall of a main chamber (1) in which an XY stage (5) on which a holder (4) holding a substrate (3) is placed, and a cylindrical sub-chamber (2). On the other hand, the side wall and (
6), through which the holder (4) freely passes through the valve (6);
The two chambers (1, 2) can be opened and closed to be airtightly separated, and the holder (2) is mounted on the other side wall of the subchamber (2).
A valve (7) that can be opened and closed for taking in and taking out the subchamber (4) and airtightly isolates it from the atmosphere is provided, and a vacuum exhaust system (8) is connected to the opening at the bottom, and inside the subchamber (2), The structure includes a hot plate (9) that heats the holder (4), and during exposure, the holder (4) is connected to the bulb (7).
is placed on the hot plate (9) to preheat it, and then placed on the XY stage (5) through the valve (6).
).) After exposure, the electron beam exposure apparatus is characterized in that the electron beam is exposed through the two bulbs (6, 7) and taken out to the outside.