JP2000150629A - Mounting/dismounting method for wefer using electrostatic chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly release a wafer from an electrostatic chuck even if a thick insulating film or a film of high dielectric constant is formed on a to-be-attracted surface side of the wafer. SOLUTION: Using an electrostatic chuck 1 which allows a dielectric body to exhibit an attractive force under a DC voltage, a wafer 2 is attracted and held, and then the wafer 2 is released from the electrostatic chuck 1. Here, before mounting/dismounting of the wafer 2 by the electrostatic chuck 1, a conductive film comprising is formed on a to-be-attracted surface 2a side of the wafer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of attaching and detaching a wafer when holding and adsorbing and releasing a wafer by an electrostatic chuck used in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art Generally, an etching apparatus, a CVD apparatus,
2. Description of the Related Art In a semiconductor manufacturing apparatus such as a sputtering apparatus, an electrostatic chuck is used to fix a wafer at a predetermined position when processing a wafer in the apparatus.

[0003] An electrostatic chuck is provided with a dielectric composed of an insulator and an electrode composed of a conductor for causing dielectric polarization in the dielectric. A DC high-voltage power supply is connected to the electrode. When a DC voltage is applied to the electrodes from a high-voltage power supply, the dielectric causes dielectric polarization, thereby exerting an attractive force. In other words, according to this electrostatic chuck, by applying a DC voltage to the dielectric to exert a suction force, the wafer can be suction-held on the dielectric.

Further, after the wafer is held on the electrostatic chuck and the desired processing is performed, the wafer is detached from the electrostatic chuck in order to remove electric charges accumulated in the electrostatic chuck. A voltage having a polarity opposite to that of the previously applied voltage is applied, or the wafer is irradiated with plasma in order to remove electric charges accumulated on the wafer.

[0005]

However, when a wafer is attached and detached by using an electrostatic chuck as described above, a thick insulating film is formed on the surface to be attracted of the wafer or the wafer has a high dielectric constant. When a film is formed, a large amount of electric charge is accumulated on the surface to be attracted by holding and adsorbing on the electrostatic chuck, so that the accumulated electric charge is completely removed even when a reverse polarity voltage is applied or plasma irradiation is performed. There is a possibility that a phenomenon in which the wafer cannot be removed and the wafer jumps on the electrostatic chuck when the wafer is separated (hereinafter, this phenomenon is referred to as “chatter”) may occur. The occurrence of such chatters may cause troubles in the process of transporting the wafer after the wafer is detached, crack the wafer itself, and the like. In other words, in the above-described conventional wafer mounting / removing method, the wafer cannot be smoothly separated from the electrostatic chuck due to the residual charge of the wafer, which may cause a transport trouble or a wafer crack.

Accordingly, an object of the present invention is to provide a method of attaching and detaching a wafer that enables the wafer to be smoothly detached from the electrostatic chuck in order to solve such a problem.

[0007]

According to the present invention, there is provided a method of attaching / detaching a wafer using an electrostatic chuck devised to achieve the above-mentioned object, wherein a static electricity is exerted on a dielectric by applying a DC voltage. A method of attaching / detaching a wafer, wherein the wafer is detached from the electrostatic chuck after adsorbing and holding the wafer on a dielectric material of the electrostatic chuck using an electric chuck. It is characterized in that a film having conductivity is formed on the surface to be attracted of the wafer.

According to the above-described procedure for attaching and detaching a wafer, since a conductive film is formed on the surface to be attracted of the wafer, electric charges are formed on the surface to be attracted by suction and holding on the electrostatic chuck. Even if the charge is accumulated, the charge is easily removed by the presence of the conductive film. That is, if the static elimination process is performed when the wafer is separated from the electrostatic chuck, the residual charge on the surface to be attracted of the wafer can be removed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for attaching and detaching a wafer using an electrostatic chuck according to the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing the relationship between the state of lamination of films formed on the surface to be attracted of a wafer and the degree of chatter generated when the wafer is detached. FIG. 2 shows the state when the wafer is attached and detached by an electrostatic chuck. FIG.

First, an outline of a method of attaching and detaching a wafer according to the present embodiment will be described. In the wafer attaching / detaching method according to the present embodiment, as shown in FIG. 2A, an electrostatic chuck 1 that exerts a suction force on a dielectric material by applying a DC voltage is used, and the wafer 2 is placed on the electrostatic chuck 1. And the wafer 2 is fixed at a predetermined position. Then, after performing a desired process such as etching, CVD, or sputtering on the wafer 2 in that state,
The wafer 2 held by suction is released from the electrostatic chuck 1.

At this time, in the electrostatic chuck 1, FIG.
As shown in (b), after performing a static elimination process by applying a voltage of reverse polarity or irradiating plasma, the electrostatic chuck 1
The wafer 2 is detached from the electrostatic chuck 1 by lifting up the lift pins 3 embedded in the wafer.
However, if a large amount of residual charge remains on the attracted surface 2a of the wafer 2 when the wafer 2 is lifted up, chattering of the wafer 2 on the lift pins 3 occurs as already described in the section of the prior art. Would.

In order to prevent this, in the wafer attaching / detaching method of the present embodiment, prior to causing the wafer 2 to be attracted and held on the electrostatic chuck 1, the wafer 2 has conductivity on the surface 2a to be attracted. A film is formed. See Figure 1
As shown in (a) to (e), the attracted surface 2a of the wafer 2
LP-TEOS (Low Pressure)
TEOS; TEOS is an abbreviation for Si (OC ₂ H ₅ ) ₄ ) PD, a polysilicon-based conductive film used for forming capacitors, etc.
An AS (Phosphine doped a-Si) film is formed in advance. As a result, the degree of chatter generated when the wafer 2 is detached is as shown in FIG.
(F) When the PDAS film is not formed, that is, as in the case of the LP-TEOS film having a thickness of 550 nm,
It can be seen that it is clearly reduced as compared with the case where the LP-TEOS film having a thickness of nm is laminated in order.

The degree of chatter here means the degree of chatter on the wafer 2. The higher the value, the greater the chatter generated. In the figure showing the chatter degree, the horizontal axis represents the number of samples (the number of wafers).

The reason why the degree of chatter can be reduced by the PDAS film on the side of the surface to be attracted 2a is as follows. That is, when the PDAS film shown in FIG. 1F is not formed, charges are accumulated by an amount corresponding to the thickness of the insulating layer (LP-TEOS film) formed on the surface to be attracted 2a (the insulating film layer). The larger the thickness, the larger the accumulated charge.) Even after performing the charge removal processing, a large amount of residual charge remains and the degree of chattering when the wafer 2 is detached increases, as opposed to FIGS. 1 (a) to 1 (e). When a PDAS film is formed, the presence of the PDAS film makes it easier to remove charges accumulated on the surface to be attracted 2a, thereby suppressing the occurrence of chattering of the wafer 2 on the lift pins 3. It is.

The position where the PDAS film is formed is preferably as close to the adsorption surface 2a as possible. This is the adsorption surface 2 more than the PDAS film.
Only the accumulated charge in the LP-TEOS film located on the side a, that is, the LP-TEOS film formed after the formation of the PDAS film is
This is because it is considered that this has affected the occurrence of chatter at the time of withdrawal.

For example, as shown in FIG. 1A, the 550 nm thick LP-TEOS film is 550 nm thick from the surface 2a to be attracted.
When the LP-TEOS film having a thickness of 300 nm and the PDAS film having a thickness of 300 nm are laminated in order, the PDAS film having a thickness of 300 nm is located between the LP-TEOS films having a thickness of 550 nm as shown in FIG. The total film thickness of the LP-TEOS film is 110
Even if it is the same as 0 nm, the case of FIG.
The thickness of the LP-TEOS film facing the electrostatic chuck 1 is 550 nm
This indicates that the chatter generated when the wafer 2 is detached is also low.

That is, the LP film formed after the PDAS film is formed
LP-TEOS facing the electrostatic chuck 1 by reducing the thickness of the -TEOS film and bringing the formation position of the PDAS film closer to the attracted surface 2a
Since the thickness of the film is reduced, occurrence of chatter when the wafer 2 is detached can be suppressed.

The thickness of the PDAS film is preferably as large as possible. This is because the thicker the PDAS film, the more the surface 2a to be adsorbed
This is because it is considered that the residual charges in the above are easily removed.

For example, as shown in FIGS. 1A and 1B, the PDAS film has a thickness of 300 nm as compared with FIG.
As shown in FIG. 7, when the PDAS film has a total thickness of 600 nm, the chatter generated when the wafer 2 is detached is also low. Further, as shown in FIGS. 1C to 1E, as the thickness of the PDAS film increases, the degree of chatter generated when the wafer 2 is detached gradually decreases. That is, as the thickness of the PDAS film is increased, occurrence of chatter when the wafer 2 is detached can be suppressed.

As described above, according to the wafer attaching / detaching method of the present embodiment, the total thickness of the LP-TEOS film is increased by forming the PDAS film on the attracted surface 2a side of the wafer 2 in advance. Even when a large amount of electric charge is accumulated, it is possible to remove the electric charge accumulated by the charge elimination process and suppress occurrence of chatter when the wafer 2 is detached. In particular, PDAS
The more the film is formed, the closer the formation position is to the attracted surface 2a of the wafer 2 or the thicker the film is, the more suitable it is to suppress chattering.

Therefore, the use of the wafer attaching / detaching method according to the present embodiment can suppress the occurrence of chattering which may cause a wafer transfer trouble or a wafer crack, and can smoothly remove the wafer 2 from the electrostatic chuck 1. Become like Further, the productivity of the semiconductor manufacturing apparatus is improved by reducing the wafer transfer trouble, and the production yield of the semiconductor device is improved by reducing the wafer cracking.

Further, even if the LP-TEOS film is formed thick on the surface 2a to be attracted of the wafer 2, the occurrence of chatter can be suppressed by forming the PDAS film. That is, the LPAS is formed on the adsorption surface 2a side by the formation of the PDAS film.
-The total thickness of the TEOS film can be increased. Therefore, the range of choice in determining the process flow in the semiconductor manufacturing process is widened, and desired device characteristics can be easily obtained.

In this embodiment, the case where the surface to be attracted of the wafer is composed of the LP-TEOS film as the insulating film and the PDAS film as the conductive film has been described as an example, but the present invention is not limited to this. It is not limited. For example, as shown in FIG. 3A, an LP-TEOS film having a thickness of 50 nm
400 nm thick LP-TEOS film, 50 nm thick LP-SiN film, 4
Even when the LP-TEOS film having a thickness of 00 nm, the LP-SiN film having a thickness of 210 nm, and the SiO ₂ film having a thickness of 300 nm are respectively laminated in this order, as shown in FIG. 100n between SiN film and 400nm thick LP-TEOS film
If a m-thick PDAS film is formed, the degree of chatter generated when the wafer is detached can be reduced.

Further, the conductive film formed on the surface to be attracted of the wafer is not limited to the polysilicon-based PDAS film. be able to. Other conductive films include, for example, titanium-based Ti widely used in a wiring forming process.
A film, a TiN film, a tungsten-based W film, a WSi film, or the like can be considered.

[0025]

As described above, according to the method of attaching and detaching a wafer using the electrostatic chuck of the present invention, a conductive film is formed on the surface to be attracted of the wafer.
Even if a large amount of electric charge is accumulated on the surface to be attracted by the adsorption and holding on the electrostatic chuck, the electric charge accumulated by the charge removal processing can be removed. Therefore, by using this wafer attaching / detaching method, even if the insulating film is formed thickly or a film having a high dielectric constant is formed on the attracted surface side of the wafer, for example, the occurrence of chattering when the wafer is detached is reduced. As a result, it is possible to realize smooth removal of the wafer from the electrostatic chuck. Further, it is possible to improve the productivity of the semiconductor manufacturing apparatus by reducing the occurrence of the wafer transfer trouble, and to improve the production yield of the semiconductor device by reducing the occurrence of the wafer crack.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the relationship between the state of lamination of films formed on a surface to be attracted of a wafer and the degree of chatter occurring when the wafer is separated, wherein (a) to (e) relate to the present invention; It is a figure which shows an example in the case of the attachment / detachment method, and (f) is a figure which shows an example in the case of not using the attachment / detachment method which concerns on this invention.

FIGS. 2A and 2B are conceptual diagrams showing an example of a state when a wafer is attached / detached by a wafer attaching / detaching method according to the present invention, wherein FIG. 2A is a diagram showing a state where a wafer is suction-held on an electrostatic chuck;
FIG. 4 is a diagram showing a state in which a wafer is detached from the electrostatic chuck.

3A and 3B are explanatory diagrams showing another example of the relationship between the state of lamination of films formed on the surface to be attracted of a wafer and the degree of chatter generated when the wafer is separated, and FIG. FIG. 4B is a diagram showing an example of a case not depending on the present invention, and FIG. 4B is a diagram showing an example of a case based on the attaching / detaching method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrostatic chuck, 2 ... Wafer, 2a ... Sucked surface

Claims (4)

[Claims] 1. An electrostatic chuck that exerts an attraction force on a dielectric material by applying a DC voltage, and after the wafer is attracted and held on the dielectric material of the electrostatic chuck, the wafer is detached from the electrostatic chuck. A method for attaching and detaching a wafer, comprising: forming a conductive film on the surface to be attracted of the wafer prior to attaching and detaching the wafer by the electrostatic chuck. How to attach and detach wafers. 2. The method according to claim 1, wherein the film is formed of a polysilicon film. 3. The method according to claim 1, wherein the film is made of a titanium-based film. 4. The method according to claim 1, wherein the film is made of a tungsten-based film.