JP2001168087A - Plasma processing apparatus and method of forming stage of plasma processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing apparatus capable of minimizing gate breakdown by making charge-up distribution on a surface of the object of the plasma processing uniform, and a method of forming a stage of the plasma processing apparatus. SOLUTION: In a plasma processing apparatus in which a stage 11 having a placement plane 11a for placing a wafer W of the object of the plasma processing is provided, the placement plane 11a has a flatness with a difference of 100 μm or smaller in height after the stage 11 is deformed at a temperature at which the apparatus is used for the plasma processing and before the stage 11 is not deformed. The stage 11 is so worked at room temperature as to keep the flatness at the plasma processing by supporting the deformation at the temperature at which the apparatus is used for the plasma processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma processing apparatus and a stage manufacturing method for the plasma processing apparatus.
In particular, the present invention relates to a plasma processing apparatus for stripping and removing a resist using plasma and a stage manufacturing method for the plasma processing apparatus.

[0002]

2. Description of the Related Art Conventionally, a plasma ashing apparatus for stripping and removing a resist using plasma has been known. This plasma ashing apparatus generates a plasma of a reactive gas, and removes a resist using the plasma.

FIG. 4 is an explanatory diagram showing a schematic configuration of a conventional plasma ashing apparatus. As shown in FIG. 4, the plasma ashing apparatus 1 has a chamber 3 made of a quartz tube and having a stage 2 on which a wafer W to be ashed is placed. In the chamber 3, a radio frequency (radio frequency:
An RF) application unit 4 is provided, and a high-frequency power supply 5 that applies high-frequency power to the outer surface of the chamber 3 is connected to the high-frequency application unit 4.

The upper end of the chamber 3 has a chamber 3
A gas inlet 3 a for introducing a process gas into the inside of the chamber 3, an exhaust port 3 b for discharging gas or the like from the inside of the chamber 3 to make a vacuum at a lower end of the chamber 3, and a side face of the chamber 3 for
A gate 6 for loading / unloading the wafer W into / from the chamber 3
Each is provided. The chamber 3 is equipped with a pressure gauge 7 for detecting the pressure in the chamber 3, and the exhaust port 3b is equipped with a pressure controller 8 for controlling the inside of the chamber 3 to a set pressure.

When the resist is stripped and removed using the plasma ashing apparatus 1, a high frequency power supply 5
A plasma is generated in the chamber 3 by applying a higher frequency power. With this plasma, the resist remaining on the wafer W after the etching process is peeled off from the wafer W.

[0006]

However, since the wafer W is subjected to charge-up damage during the ashing process using plasma, gate destruction is caused by the charge-up damage, and as a result, the yield is reduced. Invite.

This is because the stage 2 is easily deformed by heat when used in a high-temperature environment. Due to the thermal deformation, the mounting surface on which the wafer W is mounted rises upward, and the flatness of the mounting surface is deteriorated. This is because the contact between the mounting surface and the wafer W varies (see FIG. 4). When the contact between the mounting surface and the wafer W varies, the charge-up distribution on the surface of the wafer W deteriorates, and the gate is destroyed due to the potential difference on the surface of the wafer W.

As described above, the mounting surface rises upward because the stage 2 is formed in a downward cup shape having a mounting surface at the upper end, and a heat insulating member for sealing the opening is provided at the lower end with bolts or the like. This is because, due to the fixed configuration, deformation due to heat is concentrated on the mounting surface.

FIGS. 5A and 5B show distribution results of charge-up received by the wafer when the plasma ashing apparatus of FIG. 4 is used, wherein FIG. 5A is a three-dimensional explanatory view, FIG. (c) is an explanatory diagram showing the distribution state in the entire range in a table. Here, the charge amount per unit area [q / c
m ² ], and the processing conditions were as follows: RF power source power: 1400 W, gas pressure: 146.6 Pa, O ₂ flow rate: 3500 sccm, stage temperature: 240 ° C., RF
Power supply time: 60 sec.

As shown in FIG. 5, the distribution of the charge amount is always higher at the peripheral portion where the wafer W is not in contact with the mounting surface, and is higher at the central portion where the wafer W is in contact with the mounting surface. Since the lower part is lower (see (a)), the peripheral part having a height difference is more easily broken, but the central part is not much damaged. In other words, the peripheral portion that is not in contact (see (b))
Since the charge is more easily stored on the wafer W than in the central part (see (b)) where the charge is generated and in contact with the wafer W, the gate destruction proceeds due to the difference in charge amount between the central part and the peripheral part (see (c)). As a result, the peripheral portion having a large difference in height is more easily broken than the central portion.

[0011] By the way, the ashing process using plasma is also described in, for example, Japanese Patent Application Laid-Open No. 11-214.
An inductive plasma ashing processing apparatus disclosed in Japanese Patent Publication No. 361 is known. The purpose of this induction plasma ashing processing apparatus is to make the distribution of the ashing rate uniform, and it is disclosed that the diameter and the like of a discharge tube and a stage in generating plasma are set in a specific range.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma processing apparatus and a stage manufacturing method for the plasma processing apparatus which can reduce the gate breakdown by making the charge-up distribution on the surface of the plasma processing object uniform.

[0013]

To achieve the above object, a plasma processing apparatus according to the present invention is a plasma processing apparatus having a stage having a mounting surface on which a plasma processing object is mounted. The surface is characterized in that it has a flatness such that a height difference between the stage after the stage is deformed and the stage before the stage is deformed is 100 μm or less at an apparatus operating temperature during plasma processing.

With the above configuration, the mounting surface on which the plasma processing object of the stage provided in the plasma processing apparatus is mounted is deformed after the stage is deformed at the apparatus operating temperature during the plasma processing. Height difference before is 1
It has a flatness of not more than 00 μm. This makes it difficult for the mounting surface to come into contact with the plasma processing target on the mounting surface, thereby making the charge-up distribution uniform on the surface of the plasma processing target and reducing gate breakdown in the plasma processing target. .

Further, the stage of the plasma processing apparatus can be manufactured by the method of manufacturing a stage of the plasma processing apparatus according to the present invention.

[0016]

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

FIG. 1 is an explanatory diagram showing a schematic configuration of a plasma ashing apparatus according to an embodiment of the present invention. This plasma ashing apparatus 10 has a wiring width of 0.24 to
0.40 μm logic IC (integrate
d circuit) to be processed.

As shown in FIG. 1, the plasma ashing apparatus 10 has a chamber 12 made of a quartz tube and having a stage 11 on which a wafer W to be subjected to plasma ashing is mounted. The chamber 11 has a stage 11
A high-frequency power supply unit 13 for applying high-frequency power to the outer surface of the chamber 12 is connected to the high-frequency power supply unit 13.

At the upper end of the chamber 12, a chamber 12
A gas inlet 15 for introducing a process gas into the chamber 12, an exhaust port 16 for discharging gas or the like from the inside of the chamber 12 to evacuate the chamber 12 at a lower end of the chamber 12, and a side face of the chamber 12 And a gate 17 for loading / unloading the wafer W into / from the chamber 12.
The chamber 12 is equipped with a pressure gauge 18 for detecting the pressure in the chamber 12, and the exhaust port 16 is equipped with a pressure controller 19 for controlling the inside of the chamber 12 to a set pressure.

FIG. 2 is an enlarged sectional view of the stage shown in FIG. As shown in FIG. 2, the stage 11 is formed in a downward cup shape having a mounting surface 11a at an upper end.
A heat insulating member 20 and a pressing member 21 for sealing the lower end opening are fixed to, for example, bolts 22 on the outward flange 11b around the lower end opening.

The stage 11 can be freely moved up and down in the chamber 12, and an annular ashing chamber 23 is provided in the upper part of the chamber 12 to accommodate almost the entire stage 11 which has been raised during ashing. I have. An exhaust ring 23a that forms an exhaust passage is provided above the ashing chamber 23.

The stage 11 is made of, for example, aluminum (Al), and at room temperature which is not the operating temperature of the apparatus,
The mounting surface 11a is concave in a mortar shape (see the dotted line in FIG. 1).
have. That is, when the stage 11 thermally expands at a high temperature of about 240 ± 10 ° C., which is the operating temperature range of the plasma ashing apparatus 10, and the mounting surface 11 a warps so as to rise upward, the mounting surface 11 a It is previously formed in a concave shape at normal temperature so that the flatness is 100 μm or less at maximum, and desirably 50 μm or less at the time of deformation at high temperature.

The flatness shown here is 100 μm or less at maximum, and preferably 50 μm or less. The flatness is about 240 ± 10 ° C., which is the operating temperature of the apparatus, and the top of the mounting surface 11 a after the stage 11 is deformed and the stage 11 Refers to the height difference of the surface of the mounting surface 11a before deformation, and has an outer diameter of about 220 m corresponding to an 8-inch wafer W (having a maximum diameter of 220 mm).
This is the case of the stage 11 of m. Similarly, in the case of a 6-inch wafer W, the flatness of the mounting surface 11a is about 30 μm.
m, and in the case of a 12-inch wafer W, the flatness of the mounting surface 11a is preferably about 100 μm or less.

Further, the operating temperature range of the plasma ashing apparatus 10 is not limited to a high temperature of about 240 ± 10 ° C., but also includes a high temperature of about 140 ± 10 ° C. in a range of about 130 ° C. to about 250 ° C. Can respond to temperature. At this time, in accordance with the operating temperature of the apparatus, the flatness of the mounting surface 11a is set to 100 μm or less at maximum, preferably 50 μm or less at room temperature at which a flat surface can be secured during deformation at high temperature. What is necessary is just to form in a concave shape by adjusting the degree of denting in advance.

When the operating temperature of the apparatus is about 140 ± 10 ° C., the dent at normal temperature is reduced to about 240 ± 10 ° C. in accordance with the temperature.
Although it is sufficient that the concave amount is slightly smaller than that in the case of ° C, the thickness of the stage 11 is increased (for example, about 30 mm) and the mounting surface 1
By making the shape of 1a substantially flat, the flatness of the mounting surface 11a at the time of use temperature can be ensured to be 100 μm or less at maximum, preferably 50 μm or less.

The stage 11 has a cylinder 24 that penetrates through the heat insulating member 20 and the holding member 21 and is located substantially at the center of the stage 11. The cylinder 24 is slidably held by a bearing 25 disposed vertically in the chamber 12, and the stage 1 is moved through the cylinder 24.
1 can freely move up and down in the chamber 12. At the tip of the cylinder 24, a lift pin 26 stored in the stage 11 is mounted so as to be able to protrude from the mounting surface 11a. With the lift pins 26, the wafer W transferred into the chamber 12 can be received while being lifted above the mounting surface 11a.

On the back side of the mounting surface 11a of the stage 11, a heater 27 is arranged.
The wafer W (see FIG. 1) on the mounting surface 11a is heated via 1a. Below the stage 11, a bellows 28 is mounted so as to cover the bearing 25. With this bellows 28, a space 25a on the side of the bearing 25 held in an atmospheric pressure state and a space b in the chamber 12 held in a vacuum state. Separated.

When the resist is peeled off from the wafer W by using the plasma ashing apparatus 10, first,
The wafer W is transferred to the stage 11 in the chamber 12 via the gate 17 and is mounted on the mounting surface 11a of the stage 11 stored in the ashing chamber 23 via the lift pins 26.

Next, a process gas is introduced into the chamber 12 from the gas inlet 15. At this time, stage 11
Is used at a high temperature in order to improve the peeling of the resist, so that the process gas is introduced directly above the wafer W placed on the stage 11. When the process gas is introduced, the pressure in the chamber 12 is detected by the pressure gauge 18, and the pressure inside the chamber 12 is controlled to a predetermined pressure in conjunction with the pressure controller 19 provided in the exhaust gas flow path.

Next, high-frequency power is applied from a high-frequency power source 14 to the high-frequency application unit 13 to excite an ashing gas controlled to a predetermined pressure in the chamber 12 to generate plasma. Ashing processing is performed on the wafer W on the stage 11 by this plasma, and resist and the like remaining on the wafer W after the etching processing are peeled off from the wafer W. After the ashing process is completed, the wafer W is carried out of the ashing chamber 12 from the gate 17.

The plasma ashing apparatus 10 used in this ashing process has a stage shape corresponding to a single wafer type, and the stage 11 in the operating temperature range (about 130 ° C. to about 250 ° C.) of the plasma ashing apparatus 10 is used. Since the flatness of the mounting surface 11a is 100 μm or less at maximum, preferably 50 μm or less, the in-plane contact variation between the mounting surface 11a and the mounted wafer W is suppressed.

FIGS. 3A and 3B show distribution results of charge-up received by the wafer when the plasma ashing apparatus of FIG. 1 is used, wherein FIG. 3A is a three-dimensional explanatory view, FIG. (c) is an explanatory diagram showing the distribution state in the entire range in a table. Here, the charge amount per unit area [q / c
m ² ], and the processing conditions were as follows: RF power source power: 1400 W, gas pressure: 146.6 Pa, O ₂ flow rate: 3500 sccm, stage temperature: 240 ° C., RF
Power supply time: 60 sec.

As shown in FIG. 3, the distribution of the charge amount is always higher in the peripheral portion where the wafer W is not in contact with the mounting surface, and is higher in the central portion where the wafer W is in contact with the mounting surface. Since the lower part is lower (see (a)), the peripheral part having a height difference is more easily broken, but the central part is not much damaged. In other words, the peripheral portion that is not in contact (see (b))
It becomes easier to store electricity as compared to the central portion (see (b)) where charging occurs on the wafer W and makes contact.

That is, the charge-up received by the wafer is:
FIG. 3 shows the same tendency as FIG. 5, but using the plasma ashing apparatus of FIG. 1 according to the present invention (FIG. 3).
In the case of using the conventional plasma ashing apparatus (see FIG. 5), it is recognized that the charge amount is reduced in almost the entire region and is reduced as a whole, and the height difference is also reduced. (The range has changed from the range of 1.11 to 4.34 to the range of 1.02 to 3.37. See FIGS. 3 and 5 (c).) As a result, the wafer W
And the gate breakdown is reduced.

The wiring width is 0.24 to 0.40 μm.
In recent logic ICs, the gate oxide film and the like have become thinner and the gate oxide film is apt to cause dielectric breakdown. In addition, recently, the size of the wafer has been increased (8 inches). Above) and the wiring width is 0.20
Since the width tends to be narrower at 0.24 μm, dielectric breakdown is more likely to occur.

In such a situation, when the resist is removed at a higher temperature in the step of removing the resist by the plasma, the charge-up distribution on the surface of the wafer W becomes worse and the gate is destroyed. In the plasma ashing apparatus 10 described above, the charge-up distribution on the surface of the wafer W by the plasma is uniform, and the gate breakdown can be reduced.

The stage 11 of the plasma ashing apparatus 10 is manufactured by, for example, processing aluminum (Al) so that the mounting surface 11a has a concave shape in a mortar shape at room temperature. That is, the plasma ashing apparatus 10
Assuming that the stage 11 is deformed at a high temperature of about 130 ° C. to about 250 ° C., which is the operating temperature range, the flat surface 11a can be secured even at the operating temperature of the apparatus. Work at room temperature to pre-shape into a concave shape.

The stage 11 is manufactured by processing it at room temperature in advance so as to have a mortar-shaped concave shape, so that the stage 11 can be used in a temperature range of about 130 ° C. to about 250 ° C. Even when the mounting surface 11a is thermally expanded at a high temperature and warped so that the mounting surface 11a rises upward, the flatness of the mounting surface 11a is reduced by 10 at the maximum.
0 μm or less, preferably 50 μm or less.

The plasma ashing apparatus 10 having the above structure is used for plasma stripping of the resist on the wafer W. However, the plasma ashing apparatus 10 is not limited to the ashing apparatus and may be a plasma CVD (chemical vapor deposition).
plasma processing apparatus having the above-mentioned structure, such as a plasma CVD apparatus used in the above-described method.

The material of the stage 11 is not limited to aluminum (Al), but can be processed in the same manner.
What is necessary is just to be able to ensure the flatness of 1a. In addition, the stage 11 having a larger thickness is less affected by temperature and is less likely to be deformed.

As described above, according to the present invention, the stage 11 thermally expands at a high temperature of about 130 ° C. to about 250 ° C. which is the operating temperature range of the plasma ashing apparatus 10,
Even when the mounting surface 11a is warped so as to rise upward, the flatness of the mounting surface 11a is set to 100 μm at the maximum.
Hereinafter, it can be desirably ensured to be 50 μm or less. Therefore, the contact between the mounting surface 11a and the wafer W on the mounting surface 11a is less likely to vary, the charge-up distribution on the surface of the wafer W is made uniform, and gate breakage on the wafer W can be reduced.

[0042]

As described above, according to the present invention, the mounting surface of the stage provided in the plasma processing apparatus on which the plasma processing object is mounted is deformed by the temperature of the apparatus used during the plasma processing. The height difference between after and before the stage is deformed has a flatness of 100 μm or less, so that the mounting surface and the plasma processing object on the mounting surface are less likely to vary, and the surface of the plasma processing object is charged up. By making the distribution uniform, gate breakdown in the plasma processing target can be reduced.

Further, the stage of the plasma processing apparatus can be manufactured by the stage manufacturing method of the plasma processing apparatus according to the present invention.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a plasma ashing apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the stage shown in FIG.

FIG. 3 shows a distribution result of charge-up received by a wafer when the plasma ashing apparatus of FIG. 1 is used;
(A) is a three-dimensional explanatory view, (b) is a planar explanatory view,
(C) is an explanatory view showing the distribution state in the entire range in a table.

FIG. 4 is an explanatory diagram showing a schematic configuration of a conventional plasma ashing apparatus.

5 shows a distribution result of charge-up received by a wafer when the plasma ashing apparatus of FIG. 4 is used,
(A) is a three-dimensional explanatory view, (b) is a planar explanatory view,
(C) is an explanatory view showing the distribution state in the entire range in a table.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Plasma ashing apparatus 11 Stage 11a Mounting surface 11b Outward flange 12 Chamber 13 High frequency application part 14 High frequency power supply 15 Gas introduction port 16 Exhaust port 17 Gate 18 Pressure gauge 19 Pressure controller 20 Heat insulation member 21 Insulation member 21 Bolt 23 Ashing chamber 23a Exhaust ring 24 Cylinder 25 Bearing 26 Lift pin 27 Heater 28 Bellows W Wafer a Bearing side space b Chamber space

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H096 AA25 LA07 5F004 AA01 AA06 BA01 BB18 BD04 DA26 DB26 EB02 5F031 CA02 HA05 HA07 HA16 HA33 HA37 HA58 MA23 MA27 MA28 MA32 PA14 5F046 MA12

Claims (9)

[Claims] 1. A plasma processing apparatus provided with a stage having a mounting surface on which a plasma processing object is mounted, wherein the mounting surface is formed after the stage has been deformed at a device operating temperature during plasma processing. A plasma processing apparatus having a flatness such that a height difference before deformation is 100 μm or less. 2. The plasma according to claim 1, wherein the stage is preliminarily formed in a normal temperature shape so that the flatness of the mounting surface can be secured when the stage is deformed at the operating temperature of the apparatus. Processing equipment. 3. The plasma according to claim 2, wherein the normal temperature shape is a mortar-shaped shape in which the mounting surface is previously adjusted to a degree corresponding to the operating temperature of the apparatus. Processing equipment. 4. The stage according to claim 1, wherein said stage is formed in a downward cup shape having said mounting surface at an upper end, and a member for closing an opening is fixed at a lower end. The plasma processing apparatus according to any one of the above. 5. The plasma processing apparatus according to claim 1, wherein plasma separation of said plasma processing target is performed by plasma processing. 6. The plasma processing apparatus according to claim 1, wherein plasma CVD of said plasma processing target is performed by plasma processing. 7. A stage provided in a plasma processing apparatus for performing a plasma process and having a mounting surface on which a plasma processing object is mounted is provided with a stage at the time of the plasma processing, assuming deformation at an apparatus operating temperature during the plasma processing. A stage manufacturing method for a plasma processing apparatus, wherein processing is performed at normal temperature so as to secure the flatness of the mounting surface. 8. The plasma according to claim 7, wherein the mounting surface has a flatness such that a difference in height between before and after the deformation at an apparatus operating temperature during the plasma processing is 100 μm or less. Stage manufacturing method for processing equipment. 9. The stage of the plasma processing apparatus according to claim 8, wherein the mounting surface has a shape that is concave in a mortar shape whose degree of depression is adjusted in advance in accordance with the operating temperature of the apparatus. Production method.