KR20070071427A - Method for controlling temperature of electrostatic chuck - Google Patents

Abstract

A method for controlling the temperature of an electrostatic chuck is provided to minimize the thermal stress applied to a wafer by applying chucking force while the initial chucking force is gradually increased. While chucking force is gradually increased in an on-step of an electrostatic chuck, the initial chucking force is applied for a predetermined interval of time. The chucking force is applied for a shorter interval of time as the applied chucking force is increased. In applying the chucking force, 0.2 keV, 0.3 keV, 0.4 keV, 0.5 keV and 0.6 keV are used for an interval of 4 seconds, 3 seconds, 3 seconds, 3 seconds and 1 second, respectively.

Description

Method for Controlling Temperature of ElectroStatic Chuck

BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows a hotplate front pattern (electrostatic chuck pattern).

2 is a view showing a hot plate back pattern (heating pattern).

3 is an existing ESC tuning table.

4 is a graph showing the temperature effect of the conventional wafer.

5 is an ESC tuning table according to an embodiment of the present invention.

Figure 6 is a graph showing the temperature effect received by the wafer to which the present invention is applied.

The present invention relates to an ESC temperature control method. More particularly, the present invention relates to an ESC temperature control method in which an on step is dispersed in an ESC to control a step-up of a temperature received by a wafer.

Various kinds of thin films, for example, an oxide film, a nitride film, an insulating film, a metal film, and the like, are sequentially stacked on the semiconductor wafer, and each thin film is formed in a target pattern by a deposition and etching process.

In addition, it is necessary to fix the semiconductor wafer with high accuracy during the deposition and etching process. In recent years, the electrostatic chuck is mainly used because the conventional mechanical fixing device involves many problems in terms of assembly and uniformity. do. As the fixing method using the electrostatic chuck, there are a unipolar fixing method, a bipolar fixing method, and a John-Rahbek fixing method.

The deposition process using an ESC device includes an idle step, a transfer step, a chucking step, a stabilization step, a process step and a pumping step. In the fixing step, the backside argon and the ESC power are turned on, and in the stabilization step, the backside argon and the ESC power are turned on, while the pressure and the gas are turned on. After the process step is completed, first turn off the DC power, pressure and gas, then immediately turn off the backside argon and ESC power to terminate the process.

1 and 2 are views showing the front and back of the hot plate used in the ESC device.

As shown in FIGS. 1 and 2, the hot plate is composed of an assembly together with a chamber of high vacuum, ar gas, and DC power during deposition of the metal electrodes Ti, Co, and Al. It is. This hot plate is where wafers are placed, and there is an electrostatic chuck (ESC) on the front and a heating element (2) on the back, so that both wafer fixing and heating can be performed simultaneously. It is a structure that can be executed.

In this manner, the wafer chucking power of the hot plate is driven by 1.1 kW of the ESC power supply and fixed using 0.6 keV, which is about 56.4% of the maximum power. do. For example, ULVAC's sputtering equipment, the Ceraus Z-1000 and Entron W-200 Models, are examples.

By the way, the operation rule (Rule) of the conventional wafer fixation has an ESC table as shown in FIG. 3 for each recipe step (that is, a program step), and finely controls the fixation in the recipe step. For example, the ULSC system's ESC table has no vacuum chamber (Degas chamber), so the wafer at room temperature directly fixes the process chamber high temperature (350 ℃). Receiving high increases the wafer broken rate due to thermal shock.

As in the ESC table shown in FIG. 3, thermal shock is induced on the wafer by temporarily fixing the wafer at room temperature with a sudden strong force of 0.6 keV in the on step.

As described above, in order to solve the problem that the conventional ESC table is fixed to the wafer, the wafer at room temperature rises to a rapid temperature at 350 ° C. process temperature and damages the wafer to heat. By dividing the clamping force applied to the wafer to minimize the damage caused by the heat. However, even in this case, as illustrated in FIG. 4, the wafer is overshooted up to 400 ° C. within 1 second to increase the wafer stress. 4 is experimental data using a Non Contact Monitoring (NTM) system.

An object of the present invention is to control the temperature received by the wafer by distributing the on step in the ESC stepwise, and to lower the initial power of the on step than the fixed power which is generally applied to solve the problem of initial overshooting It is to provide an ESC temperature control method applied.

In the ESC temperature control method according to the present invention, in the ESC On step, the raising force (Chucking force) is increased in stages, an initial fixing force is applied for a set time, and the applied fixing force is increased than the set time as the applied fixing force increases. It is characterized by a short application.

At this time, the step of applying the fixing force, 0.2keV for 4 seconds, 0.3keV for 3 seconds, 0.4keV for 3 seconds, 0.5keV for 3 seconds, it is preferable to form 0.6keV for 1 second. Do.

Embodiment

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 is an ESC tuning table according to an embodiment of the present invention, and FIG. 6 is a graph showing a temperature effect of a wafer to which the present invention is applied.

As shown in FIG. 5 and FIG. 6, basically, the fixing force is changed from low to high in the ESC on step to minimize thermal shock to the wafer. That is, it can be seen that the temperature control is stabilized as compared to the existing control method.

To this end, in the wafer chuck on step, heat transfer occurs to the wafer within 1 second, and it can be seen that overshooting is performed within 300 ° C. In other words, the initial clamping force is applied for 4 seconds (sec) at 0.2 keV, 3 seconds at 0.3 keV, 3 seconds at 0.4 keV, 3 seconds at 0.5 keV, and 1 second at 0.6 keV at initial room temperature. Applying in stages minimizes thermal damage to the wafer. This can be seen as a thermal aging effect on the wafer, and subsequent steps create stepwise temperature rise. This can be obtained by initially applying a small fixing force for a relatively long time and applying a short distribution of time as the fixing force rises. On the other hand, the 0.6keV holding force corresponding to the continuous on step is made in the on step process will be able to ensure the speed of the process.

As such, the initial chucking force acts as an important factor in inducing overall wafer stability.

Although specific embodiments of the present invention have been described with reference to the drawings, this is intended to be easily understood by those skilled in the art and is not intended to limit the technical scope of the present invention. Therefore, the technical scope of the present invention is determined by the matters described in the claims, and the embodiments described with reference to the drawings may be modified or modified as much as possible within the technical spirit and scope of the present invention.

According to the present invention, it is possible to minimize the thermal stress that the wafer can initially receive by applying an initial chucking force while raising the stage step by step. In addition, temperature aging may also be expected by increasing the holding force in stages. As a result, it is possible to prevent wafer thermal shock that occurs in the hot plate pattern type.

Claims (2)

The electrostatic chuck on step increases the chucking force step by step, applies an initial fixing force for a set time, and applies a shorter time than the set time as the applied fixing force increases. Temperature control method of the electrostatic chuck. The method of claim 1, wherein the fixing force is applied to 0.2 keV for 4 seconds, 0.3 keV for 3 seconds, 0.4 keV for 3 seconds, 0.5 keV for 3 seconds, and 0.6 keV for 1 second. An electrostatic chuck temperature control method.

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