JPH0311750A - Sample suction holder - Google Patents

Abstract

PURPOSE:To enhance the cooling power of a holder and to enhance the electrostatic force annihilation characteristic of the holder by a method wherein an insulating dielectric part constituting the holder is constituted into a composite structure consisting of a first insulator component for covering integrally all the peripheries of electrodes and a second insulator component for forming a sample suction part. CONSTITUTION:Electrodes 21 for applying a DC voltage are completely covered and insulated with a first insulating dielectric component 22 consisting of a sintered Al oxide. Moreover, a second high-insulating dielectric component 23, which has an elasticity and a flexibility and consists of a capton film, is arranged on the upper surface of the component 22 and the surface of the component 23 is used as a sample suction surface. In order to use a suction holder, a sample S is placed on lift pins 25, the pins 25 are made to descend and the sample S is transferred on the suction surface. After that, desired positive and negative voltages are applied to the electrodes 21 to generate an electrostatic charge in the sample suction surface and the sample S is sucked by an electrostatic force and is cooled. After that, the sample S is recovered. Thereby, both conditions of a securement of a high cooling power and a fast electrostatic force annihilation characteristic can be simultaneously satisfied and the throughput of a device can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical field to which the invention pertains The present invention relates to a sample suction holder for fixing and cooling a sample essential for LSI manufacturing equipment and the like.

(2) Conventional technology and its problems In order to reduce the production cost of LSI, etc., an apparatus that can process a large amount of samples in a short time is required.

For example, an etching apparatus is required to satisfy the following conditions: (1) high etching speed, and (2) short sample exchange time.

However, in order to ensure a high etching rate, it is necessary to irradiate the sample with high-density plasma for etching, and if the sample is poorly cooled, the sample temperature will rise significantly, causing thermal damage to the resist. Therefore, in order to solve this problem, a sample suction holder with high cooling capacity is required, and recently, sample suction holders that utilize electrostatic force, which can obtain an adhesion force proportional to the applied voltage (DC), have been used. It has become.

However, with conventional electrostatic sample suction holders, ■ it is difficult to apply high voltage and it is difficult to ensure sufficient cooling capacity, or ■ the electrostatic force remains on the sample for a very long time after the applied voltage is removed. It had drawbacks such as requiring a long time to replace it.

Below, we will discuss the structure of a conventional electrostatic adsorption sample holder and experimental results regarding its cooling performance and residual electrostatic force characteristics.

In the experiment, a two-electrode electrostatic sample suction holder was installed in an ECR discharge type etching device equipped with an automatic wafer transfer mechanism, and St was etched using the resist as a mask using the μ-wave power and the applied voltage for sample suction as parameters. The cooling capacity and residual electrostatic force characteristics of each holder were evaluated.

The cooling capacity was evaluated by examining the limit of the power that can be input without causing thermal damage to the resist. In addition, the electrostatic force residual characteristics were evaluated based on the waiting time from when the applied voltage was removed to when the sample collection became possible.

FIG. 1 shows an example of the structure of a conventional electrostatic sample suction holder. Only the Kapton film 3 is used as the insulating dielectric component necessary to generate electrostatic force.
and sample 5 (Si wafer). A
! Another simple insulator 2 is used for insulation between the electrodes 1 and between the lower part of the electrodes and the cooling channel component 5. 6 is a lift pin.

A drawback of this holder is that the insulating dielectric component placed between the electrode top and the sample and other insulating components are not formed as an integral component, so that a bonding surface 4 exists that connects the electrodes. Due to this structure, when a positive and negative high voltage is applied between the electrodes, an abnormal discharge occurs along the joint surface of the parts, causing a short circuit between the electrodes, and the sample suction holder itself becomes unusable immediately. . For this reason, the sample cooling capacity was also limited, and the power that could be inputted to allow etching without thermal damage to the resist was limited to 600W.

FIG. 2 shows an example of another conventional sample suction holder developed to solve the drawbacks of the sample holder described above. The entire periphery of the electrode 11 (W) is surrounded by one highly insulating dielectric component 12 made of sintered aluminum oxide. 13 is a cooling channel component, and 14 is a lift pin. With this structure, there is no component bonding surface that connects the electrodes, and sufficient dielectric strength can be ensured between each component, making it possible to apply high voltage. As a result, by securing a large electrostatic adhesion force by applying a high voltage and securing a high cooling capacity by the cooling channel component 13, it is possible to apply a large power of 1200 W or more without thermal damage to the resist, and the holder ( It is now possible to obtain an etching rate that is approximately twice as high as that in Figure 1).

However, although this holder has made it possible to ensure high cooling performance due to large electrostatic force, the electrostatic force remains for a very long time (
For example, under the condition of applying a DC voltage of ±1.5 KV, the electrostatic force between the sample and the electrostatic sample suction holder does not disappear for more than 5 minutes, resulting in a new drawback that it takes a long time to exchange the sample. .

As described above, the conventional electrostatic sample suction holder has the disadvantage that it cannot simultaneously satisfy both the requirements of high cooling capacity and fast electrostatic force dissipation characteristics.

(3) Purpose of the Invention The purpose of the present invention is to solve the drawback of the conventional electrostatic sample suction holder that it cannot simultaneously satisfy both conditions of high cooling capacity and fast electrostatic force dissipation property, and to put it into practical use that satisfies both conditions at the same time. The object of the present invention is to provide a sample adsorption holder.

(4) Structure of the Invention (4-1) Characteristics of the Invention and Differences from the Prior Art The present invention achieves ■ ensuring high cooling performance by devising the structure of the insulating dielectric part in an electrostatic sample suction holder. The object of the present invention is to realize a sample suction holder that is characterized by simultaneously satisfying both of the following conditions: (1) Improving the efficiency of sample exchange by shortening the electrostatic residual time.

Specifically, the insulating dielectric component placed between the DC voltage applying electrode and the sample in the electrostatic sample suction holder has a composite structure, and one insulating dielectric material covers the entire two electrodes. Completely enveloping the electrodes prevents abnormal discharge between the electrodes, making it possible to apply high voltage, while configuring the sample adsorption surface with an elastic and flexible insulating dielectric material to prevent positive and negative residual charges when collecting the sample. The purpose is to efficiently combine and eliminate the electrostatic force, shorten the electrostatic force residual time, and improve sample exchange efficiency. That is, the main feature of the present invention is that it is a sample holder with high cooling ability and short electrostatic force residual time. It differs greatly from conventional electrostatic sample suction holders in that both conditions can be met at the same time.

(4-2) Example Figure 3 is a structural diagram of the electrostatic sample adsorption holder of the present invention, in which 21 is a DC voltage applying electrode, 22 is ensuring insulation between the DC voltage applying electrode and other parts. 23 is a second highly insulating dielectric component forming a sample adsorption surface disposed between the first highly insulating dielectric component and the sample; 24 is a cooling component; Waterway parts, 25 is a lift bin,
S is a sample.

DC voltage application electrode 2 located in the center of the electrostatic sample adsorption holder
1 is made of tungsten (-) that can withstand high-temperature sintering, and the entire periphery of the electrode is completely covered and insulated with a first insulating dielectric part 22 made of sintered aluminum oxide, which is a highly insulating dielectric material. There is. Further, a second highly insulating dielectric component 23 made of an elastic and flexible Kapton film is disposed on the upper surface of the first insulating dielectric component 22, and its surface is used as a sample attraction surface.

Further, the lower surface of the first insulating dielectric component 22 is in contact with the cooling channel component 24 .

To use this electrostatic sample suction holder, first place the sample S on the lift pin 25 located above the sample suction surface, and lower the lift pin 25 to remove the sample S.
Transfer it onto the suction surface. After that, the DC voltage application electrode 2
A desired positive and negative voltage is applied to the sample S to generate an electrostatic charge on the sample adsorption surface, and the sample S is adsorbed by the electrostatic force and cooled.

To collect the sample S, first, the DC voltage applied to attract the sample S is released, and the system waits until the electrostatic force disappears.

Thereafter, the sample S is moved from the suction surface onto the lift bin 25 by being lifted while supporting the outer circumferential portion of the sample with the lift pins 25, and collected by a transport mechanism or the like.

Below, an example of the results of an experiment conducted to compare the cooling performance and electrostatic force residual characteristics (sample exchange efficiency) of conventional sample holders (A), (B) and the sample holder (C) of the present invention will be shown.

As already mentioned, the cooling performance is determined by placing a sample (Si wafer with a resist button) on each sample holder and cooling it.
By irradiating the sample with C12 plasma, evaluation was made based on the power that can be applied to etching the resist without thermal damage. As a result, in the conventional sample holder (A) having a component joining surface between electrodes, the power that could be applied was limited to 600W due to the occurrence of abnormal discharge. In addition, with the conventional sample holder (B) that uses an integrally formed highly insulating dielectric component made of sintered aluminum oxide with no component joint surface between the electrodes, there is no problem with abnormal discharge, and the input power is 1200 W. There was no problem with the above.

On the other hand, although the power that can be applied to the sample holder (C) of the present invention was not as high as that of the sample holder (B), it was 900 W, which is 1.5 times that of the sample holder (B), and the power was sufficient for etching Si. (1,500 people/minute).

Figure 4 shows the sample holder of the present invention (C) and the conventional sample holder (C) regarding the electrostatic force residual characteristics related to sample exchange time.
This is a comparison of the differences.

Here, the electrostatic force residual time is defined as the waiting time from the time when the DC applied voltage is removed until the electrostatic force disappears, the sample is moved above the sample holder by the lift pin, and can be recovered by the transport mechanism.

As a result, it was found that the sample holder (C) of the present invention requires only a very short waiting time of 15 seconds at most even when ±2 KV is applied, and the sample can be replaced in a short time.

In contrast, with the conventional sample holder (B), ±0.5K
V application requires 2 minutes, ±0.75 K V application requires 3 minutes, and ±2 ■ application requires a long waiting time of 5 minutes or more, and under such application conditions, the sample exchange time is too long to be practical. It was found that this method could not be used in other types of equipment.

Therefore, in order to shorten the sample exchange time in the sample holder (B), the applied voltage was reduced to 0. I tried to reduce it to about IKV, but
Since the sample cooling capacity was very small, the power that could be applied without causing thermal damage to the resist was extremely small, making it impossible to obtain a sufficient etching rate. Further, since the reduction in adhesion makes it difficult to adsorb large samples, the conventional sample holder (B) cannot be used in the current LSI manufacturing equipment that uses large diameter wafers.

This difference in electrostatic force residual characteristics is due to the fact that the second highly insulating dielectric component is made of an elastic and flexible highly insulating dielectric material that acts as a sample adsorption surface on top of the first highly insulating dielectric component. We believe this is a result of the placement of parts (for example, Kapton membrane). In other words, even if the sample is pushed up with a lift pin immediately after the applied voltage is removed, the adsorption surface and the sample can easily undergo instantaneous shape deformation, making it easy for positive and negative electrostatic charges to recombine and disappear. Residual electrostatic force disappears in a short time, making it possible to exchange samples in a short time.

As a result, we have achieved an electrostatic sample suction holder device that can simultaneously satisfy both the requirements of ensuring high cooling capacity, which could not be achieved with conventional sample holders, and increasing the efficiency of sample exchange by shortening the electrostatic residual time.

The sample holder of the present invention has a structure in which other holder components are coated with a polymer film (Kapton film, etc.) that does not contain heavy metal substances, so parts that are likely to be contaminated by heavy metals are not exposed to plasma. There is also the advantage that impurity contamination from the sintered insulating dielectric component, which is likely to be a problem with the conventional sample holder (B), can be completely prevented since it can be prevented from occurring. In addition, this polymer membrane can be easily adhered with silicone adhesive, and is also easy to peel and re-adhere, making it much cheaper to manufacture and recycle than conventional membranes. There is also the feature that it can be done.

(5) As described in detail, the electrostatic sample adsorption holder of the present invention has the following features:
It has the advantage of being able to simultaneously satisfy both of the following conditions: (1) ensuring high cooling capacity and (2) fast electrostatic force dissipation characteristics (reducing replacement time), thereby improving the throughput of the device. Another advantage is that the sample adsorption surface can be manufactured and reproduced easily and inexpensively.

[Brief explanation of drawings]

Figure 1 is a structural diagram of a conventional electrostatic sample suction holder that has a component bonding surface between the electrodes, and Figure 2 shows the electrode covered with one highly insulated dielectric component and has no component bonding surface between the electrodes. FIG. 3 is a structural diagram of a conventional electrostatic sample holder, FIG. 3 is a structural diagram of an electrostatic chuck sample holder using the composite structure insulating dielectric component of the present invention, and FIG. 4 is a diagram showing the electrostatic force residual characteristics of each sample holder. FIG. 3 is a characteristic diagram showing experimental results. 1... DC applying electrode (Al), 2... Insulating component for insulating only the lower part of the electrode and between the electrodes, 3... Highly insulating dielectric component placed between the lower part of the electrode and the sample (Kapton film) ,
4... Component joining surface existing between electrodes, 5... Cooling channel component, 6... Lift bottle, S... Etching sample, 11... Direct current application electrode (W), 12... Electrode Highly insulating dielectric component (sintered aluminum oxide) that integrally insulates the whole, 13... Cooling channel component, 14... Lift pin, 21... DC applied electric current i (W), 22...
a first highly insulating dielectric component (sintered aluminum oxide) that integrally insulates the entire electrode; Highly insulating dielectric parts (Kapton film), 24...Cooling channel parts, 25...Lift bin.

Claims (3)

[Claims] (1) In a sample suction holder that uses electrostatic force, the insulating dielectric parts that constitute the holder include a first insulating dielectric part that integrally covers the entire circumference of the electrode, and a second insulating dielectric part that forms the sample suction part. A sample suction holder characterized by having a composite structure with insulating dielectric parts. (2) The sample suction holder according to claim 1, wherein the second insulating dielectric component is a polymer film such as Kapton. (3) The first insulating dielectric component is aluminum oxide formed by an anodizing method or a sintering method, and the second insulating dielectric component is a polymeric insulating dielectric film such as Kapton. A sample suction holder according to claim 1, characterized in that: