JP2002241946A - Plasma processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing apparatus which can improve the uniformity of the intra-plane film thickness of plasma treatment, for example, plasma CVD processing, and also improve the product yield. SOLUTION: The plasma processing apparatus is provided, in a treatment vessel 22 which can be evacuated, with a lower electrode 44 functioning also as a plate on which a body W to be treated is placed and an upper electrode 26, and applies high-frequency voltage between both electrodes to perform plasma treatment on the body to be treated. In the peripheral part of the lower electrode, a focusing ring 66 is provided with a prescribed interval on the outside from the outer periphery end surface of the body to be treated, wherein the prescribed interval is set within a range of 10 to 27 mm. This configuration realizes the improvement of the intra-plane uniformity of the film thickness of plasma treatment, for example, plasma CVD processing, and improvement of the product yield.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a plasma processing apparatus for performing a plasma processing on a semiconductor wafer, for example.

[0002]

2. Description of the Related Art In general, in order to manufacture a semiconductor integrated circuit, various heat treatments such as film formation, etching, oxidative diffusion, annealing, etc. are repeatedly performed on a semiconductor wafer, and a plasma process for performing this type of process is performed. The apparatus is disclosed in, for example, JP-A-8-339895 and JP-A-8-181107. For example, CVD (Chemi) for depositing a film on each wafer using plasma.
In a cal vapor deposition (cal vapor deposition) apparatus, a semiconductor wafer is mounted on a mounting table such as a susceptor having a built-in heater, and a processing gas for film formation is supplied while heating the semiconductor wafer to a predetermined temperature. Is applied between the upper electrode and the lower electrode also serving as a mounting table to generate plasma and deposit a film on the wafer surface. This will be described with reference to FIG.

FIG. 13 is a schematic structural view showing a conventional general plasma processing apparatus. This plasma processing apparatus has a substantially cylindrical processing vessel 2 which can be evacuated. A lower electrode 4 also serving as a mounting table for mounting the semiconductor wafer W on the upper surface is installed in the processing container 2, and a film forming gas or the like is provided in the processing container 2 on a ceiling facing the lower electrode 4. An upper electrode 6 also serving as a shower head for supplying the processing gas is provided via an insulating material 8.
A high-frequency power supply 12 of, for example, 450 KHz is connected to the upper electrode 6 via a matching circuit 10.

The entire lower electrode 4 is made of ceramics such as AlN (aluminum nitride), for example, and a heater 14 made of a resistor such as a molybdenum wire is embedded in the inside thereof in a predetermined pattern. At the same time, for example, an electrode body 16 in which molybdenum wires are arranged in a mesh shape is embedded. Then, the processing gas is evacuated to a predetermined pressure while supplying the processing gas into the processing container 2, the wafer W is directly placed on the lower electrode 4 formed as described above, and the wafer W is heated by the heater 14. While heating, a high-frequency voltage is applied between the upper electrode 6 and the lower electrode 4 to generate a plasma to perform a film forming process.

[0005]

By the way, when performing a film forming process by plasma CVD on the wafer W, it is necessary to ensure in-plane uniformity of the film thickness. In particular, recently, further miniaturization of the line width and thinning of the film thickness have been demanded, and further improvement in the in-plane uniformity of the film thickness has been desired. However, in the conventional apparatus as described above, the in-plane uniformity of the film thickness cannot be sufficiently improved due to the non-uniformity of the distribution of the plasma formed in the processing chamber 2 and the like. There was such a problem. In addition, due to the non-uniform distribution of plasma in the processing chamber 2 or the non-uniform distribution of the film thickness to be deposited, an excessive potential difference may be generated in the wafer surface. There is also a problem in that electrical breakdown occurs in the insulating film or the like, which is called charge-up damage, and the product yield is reduced. The present invention has been devised in view of the above problems and effectively solving them. An object of the present invention is to provide a plasma processing apparatus capable of improving the in-plane uniformity of the film thickness of plasma processing, for example, plasma CVD processing, and improving the product yield.

[0006]

According to the present inventors, the plasma state of the processing space depends on the capacitance between the upper surface of the focus ring and the upper electrode and the exposure of the surface of the mounting table inside the focus ring. The present invention has been achieved by obtaining the finding that the capacitance is greatly affected by the ratio between the capacitance between the portion and the upper electrode. The invention defined in claim 1 is to provide a lower electrode also serving as a mounting table for mounting an object to be processed and an upper electrode in a processing chamber which can be evacuated, and apply a high-frequency voltage between the two electrodes. In the plasma processing apparatus, the plasma processing apparatus is configured to apply the plasma processing to the processing target by applying a predetermined distance to a peripheral portion of the lower electrode outside a peripheral end surface of the processing target by a focus ring. And the predetermined interval is 10 to 27 m
It is configured to be set within the range of m. As a result, the distribution state of plasma in the processing space in the processing chamber is optimized, and not only the in-plane uniformity of the plasma processing can be improved, but also the occurrence of charge-up damage is suppressed and the product yield is improved. It is possible to do.

In this case, for example, the focus ring is made of an insulating material, and its thickness is set in a range of 0.2 to 5 mm. Claim 3
The present invention provides a plasma processing apparatus for performing a plasma process on an object to be processed in a processing chamber capable of being evacuated, comprising: an upper electrode; and a first dielectric for mounting the object to be processed. A mounting table serving also as a lower electrode, which is formed of a body;
A plasma processing apparatus characterized in that an annular focus ring made of a second dielectric is provided at a predetermined interval within a range of up to 27 mm. In this case, for example, as defined in claim 4, the focus ring is formed separately from the mounting table and is fitted to a peripheral portion of the mounting table. Alternatively, for example, as set forth in claim 5, the mounting table and the focus ring are made of a dielectric having the same dielectric constant, and both are integrally formed. Also, for example, as defined in claim 6,
The mounting table is provided with a convex positioning protrusion for positioning an outer peripheral end of the object to be processed. Alternatively, for example, as set forth in claim 7, the mounting table is provided with a positioning step portion for positioning an outer peripheral end of the object to be processed.
Further, for example, as defined in claim 8, the upper electrode also serves as a shower head for introducing a predetermined gas into the processing container.

Further, for example, as defined in claim 9,
The plasma processing is a plasma CVD processing for depositing a thin film on the surface of the object. According to this, since plasma CVD is performed as a plasma process, not only the in-plane uniformity of the deposited film can be improved by optimizing the plasma distribution state, but also in this case, the charge-up damage can be improved. It is possible to improve the yield of products by suppressing the occurrence of cracks. Further, as defined in claim 10, the predetermined interval is in a range of 10 to 27 mm. Furthermore, the dielectric constant of the first dielectric is set to be smaller than the dielectric constant of the second dielectric.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the plasma processing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. Figure 1
FIG. 2 is a sectional view showing a plasma processing apparatus according to the present invention, FIG. 2 is a perspective view showing a focus ring, and FIG. 3 is a partially enlarged sectional view of the plasma processing apparatus. Here, a plasma CVD film forming apparatus will be described as an example of the plasma processing apparatus. As shown in the figure, a plasma CVD film forming apparatus 20 as this plasma processing apparatus has a processing container 22 formed of, for example, aluminum into a cylindrical shape. A shower head 26 having a large number of gas outlets 24 on the lower surface is provided on the ceiling of the processing container 22.
Thereby, for example, a film forming gas or the like can be introduced into the processing space S in the processing container 22 as the processing gas.
Note that a diffusion plate may be provided in the shower head 26.

The entire shower head 26 is made of a conductor such as nickel, Hastelloy (trade name), aluminum, carbon, graphite, etc., and also serves as an upper electrode. The outer peripheral side and the upper side of the shower head 26 serving as the upper electrode are entirely covered with an insulator 28 made of, for example, quartz or alumina (Al ₂ O ₃ ), and the shower head 26 is made of this insulator. It is attached and fixed in an insulated state to the processing container 22 via 28. In this case, for example, O is provided between the joints of the shower head 26, the insulator 28, and the processing container 22.
A seal member 30 made up of a ring or the like is interposed therebetween so as to maintain airtightness in the processing container 22. A high-frequency power supply 34 for generating a high-frequency voltage of, for example, 450 KHz is connected to the shower head section 26 via a matching circuit 32. The high-frequency voltage is supplied to the shower head section 26 as the upper electrode as necessary. It is designed to be applied. The frequency of the high-frequency voltage is not limited to 450 KHz, and another frequency, for example, 13.56 MHz may be used.

On the side wall of the processing container 22, there is formed a loading / unloading port 36 for loading / unloading a wafer, and a gate valve 38 is provided in the loading / unloading port 36 so as to be opened and closed. A load lock chamber and a transfer chamber (not shown) are connected to the gate valve 38. An exhaust port 40 connected to a vacuum pump or the like (not shown) is provided at the bottom of the processing container 22.
The inside of the processing container 22 can be evacuated as needed. In order to place a semiconductor wafer W as an object to be processed, the column 4
The mounting table 44 is provided upright through the mounting table 2. The mounting table 44 also serves as a lower electrode, and plasma can be generated by a high-frequency voltage in a processing space S between the mounting table 44 as the lower electrode and the shower head 26 as the upper electrode. . Specifically, the mounting table 4
Reference numeral 4 denotes a first dielectric, for example, a ceramic such as AlN, and a heater 46 made of a resistor, such as a molybdenum wire, is embedded and arranged in a predetermined pattern. A heater power supply 48 is connected to the heater 46 via a wiring 47 so as to supply electric power to the heater 46 as needed. Further, inside the mounting table 44,
For example, an electrode main body 50 in which a molybdenum wire or the like is meshed (meshed) is buried in substantially the entire area in the in-plane direction. The electrode body 50 is grounded via the wiring 52. Note that a high-frequency voltage may be applied to the electrode body 50 as a bias voltage.

The mounting table 44 has a plurality of pin holes 54 penetrating in the vertical direction. Each of the pin holes 54 has a lower end commonly connected to a connection ring 56, for example, quartz. Push-up pin 58 is accommodated in a loosely fitted state. The connecting ring 56 is connected to an upper end of a retractable rod 60 that penetrates the bottom of the container and is provided so as to be vertically movable. The lower end of the retractable rod 60 is connected to an air cylinder 62. Thus, each push-up pin 58 is made to protrude upward from the upper end of each pin hole 54 when the wafer W is transferred. An extendable bellows 64 is interposed at the penetrating portion of the retractable rod 60 with respect to the container bottom, so that the retractable rod 60 can move up and down while maintaining the airtightness in the processing container 22. ing. A focus ring 66, which is a feature of the present invention, is provided at a peripheral portion of the mounting table 44, which is a lower electrode, at a predetermined distance L1 (see also FIG. 3) outside the outer peripheral end surface of the semiconductor wafer W. Is provided. Specifically, this focus ring 66
For example, alumina (Al ₂ O ₃ ), aluminum nitride (Al
N) or a second dielectric which is an insulating material such as quartz, preferably alumina. The focus ring 66 has an inverted L-shaped cross section, and is formed in a circular ring shape as shown in FIG. The focus ring 66 is fitted almost in close contact with the corner of the peripheral edge of the upper surface of the mounting table 44.

Here, the diameter of the mounting table 44 is set to be substantially the same as the diameter of the shower head section 26 arranged opposite thereto.
In the case of inch (20cm), both are 260m
m. The important point here is that, as shown in FIG. 3, the predetermined distance L1, ie, the outer peripheral end face 70 of the wafer W and the inner end face 66 of the focus ring 66,
The point is that the distance L1 from the distance A is set in a range of 10 to 27 mm, preferably in a range of 15 to 22 mm.
In this manner, the focus ring 66 made of an insulating material is fitted around the periphery of the mounting table 44 forming the lower electrode,
By limiting the exposed area of the upper surface of the mounting table 44 to an appropriate size, it is possible to form plasma in an appropriate distribution state in the processing space S between the mounting table 44 and the upper electrode 26 above. In this case, the portion where the wafer W is actually placed has a slight depth H1, for example, within a range of about the thickness of the wafer, preferably about 0 to 0.75 mm, and 0.6 m in FIG.
A mounting recess 68 recessed by about m is formed so that the wafer W can be accurately positioned. Here, an example of the dimensions of each part is specifically shown. The thickness L2 of the focus ring 66 is in the range of about 0.2 to 5 mm, preferably in the range of about 0.5 to 3 mm. The length L3 of the horizontal portion extends in the outer peripheral direction from a point within a range of about 3 to 20 mm, preferably a distance L1, and extends to the same position as the end of the shower head 26. The thickness L4 of the wafer W is approximately 0.75 mm, and the distance L5 between the upper surface of the mounting table 44 and the lower surface of the shower head 26 is approximately 14.25 mm. Also,
The distance L6 between the lower surface of the shower head 26 and the surface of the wafer is approximately 13.56 mm. Further, the distance L7 between the lower surface of the shower head unit 26 and the upper surface of the focus ring 66 is in a range of about 9 to 14.05 mm, for example, about 12.65 mm. Also, shower head 2
The size of each of the above-mentioned lengths L1, L3 and L1 with respect to the focus ring 66 is optimized by changing the distance between the mounting ring 6 and the mounting table 44, the wafer surface, the focus ring 66 and the like.

Next, the operation of the embodiment constructed as described above will be described. First, the gate valve 38 provided on the side wall of the processing container 22 is opened, and an unprocessed semiconductor wafer W is loaded into the processing container 22 from a load lock chamber (not shown) via the loading / unloading port 36 and pushed up. The wafer W is mounted on the mounting table 44 serving as a lower electrode by being transferred to the pins 58 and lowered. next,
The inside of the processing container 22 is sealed, the power supplied to the heater 46 is increased, and the mounting table 44 that has been preheated in advance is set.
Temperature is raised to and maintained at the process temperature. And
At the same time, a film-forming gas or the like whose flow rate is controlled as a processing gas from the shower head 26 serving as an upper electrode is supplied to the processing vessel 22
At the same time, the inside of the processing container 22 is evacuated from the exhaust port 40 to maintain the inside of the processing container 22 at a predetermined process pressure. When depositing a thin film of a Ti metal film or a Ti compound metal film, for example, TiCl ₄ , He, Ar, H ₂ , N ₂ , NH ₃ or the like is used as the film forming gas.

At the same time as the above operation, the high-frequency power supply 34 is driven to apply a high-frequency voltage of, for example, 450 KHz between the shower head 26 as the upper electrode and the mounting table 44 as the lower electrode. As a result, a plasma is set up in the processing space S, the TiCl ₄ gas is decomposed by the active species generated at this time, and a thin film is deposited on the surface of the wafer W. In the case where such a film forming process is performed, in the present embodiment, the focus ring 66 made of an insulating material whose size and size is optimized is provided on the peripheral portion of the mounting table 44. In addition, the plasma distribution in the processing space S can be set to an optimum state, whereby not only the in-plane uniformity of the plasma processing, that is, the in-plane uniformity of the thickness of the deposited film can be improved, but also Since a large potential difference can be prevented from being generated on the wafer surface, the occurrence of charge-up damage can be suppressed, and the yield can be improved.

In this case, the optimum size of the focus ring 66 is, as described above, such that the distance L1 between the outer peripheral end surface 70 of the wafer W and the inner end surface 66A of the focus ring 66 is within the range of 10 to 27 mm. By setting as described above, the distribution density of the plasma is optimized, and the in-plane uniformity of the film thickness and the yield can be improved as described above. Here, the thickness uniformity of the deposited film when the distance L1 was changed by variously changing the size and size of the focus ring 66 was obtained by actually depositing a Ti metal film. The evaluation result at that time will be described. Here, AlN having a dielectric constant of 7 to 9 was used as the mounting table 44, and Al ₂ O ₃ having a dielectric constant of 8 to 10 was used as the focus ring 66. Further, in the heated state, the dielectric constant further decreases, especially in the case of AlN, to about half, and Al ₂ O ₃ does not decrease so much. Therefore, Al
The difference in the dielectric constant between N and Al ₂ O ₃ is further increased, and the effect of improving the uniformity of the plasma density can be enhanced. FIG. 4 is a graph showing the relationship between the distance L1 between the outer peripheral end surface of the wafer and the inner peripheral end surface of the focus ring and the in-plane uniformity of the film thickness. Here, the dimensions of the other parts were the same as those shown in FIGS. 1 and 3, and the wafer size was 8 inches (20 cm). Further, the in-plane uniformity of the film thickness was obtained by measuring a sheet resistance depending on this. As is clear from the graph shown in FIG.
When the distance L1 is gradually reduced by increasing the upper surface of the focus ring toward the wafer side from 30 mm (in a state where the focus ring is not installed), the in-plane uniformity of the film thickness also gradually decreases, and the distance L1 is reduced. When the thickness is about 18 mm, the in-plane uniformity of the film thickness shows the best value (about 5%). If the distance L1 is further reduced, the in-plane uniformity of the film thickness will gradually increase.

Therefore, the upper limit of the in-plane uniformity of the film thickness is set to 10
%, The appropriate range of the distance L1 is 10 to 27 mm
It has been found that the optimum value is about 15 to 22.5 mm (in-plane uniformity of film thickness is within 6%). When the product yield was determined by setting the distance L1 to 20 mm, the defect rate was about 45% in the conventional apparatus, but the defect rate was about 0% in the apparatus of the present invention, and the product yield was greatly improved. It turns out that it can be done. Here, the distribution state of the plasma when the distance L1 is variously changed will be schematically described. FIG. 5 is a diagram schematically showing the relationship between the plasma distribution state and the film thickness on the wafer when the distance L1 is variously changed. In the figure, the distance L1 is 10, 20, 25.
5A and 30 mm (in a state where the focus ring is not installed). FIG. 5A shows a case where the distance L1 is 25 and 30 mm, and FIG. 5B shows a case where the distance L1 is 20 mm.
In (C), the distance L1 is 10 mm. In the drawing, P indicates the distribution state of the plasma, 80 indicates the deposited film, and T indicates the difference between the maximum value and the minimum value of the film thickness.

As shown in FIGS. 5A and 5C, even if the distance L1 is too large, such as 25 mm and 30 mm,
Alternatively, even if the thickness is too small such as 10 mm, the thickness difference T increases together, which is not preferable from the viewpoint of in-plane uniformity of the film thickness. On the other hand, as shown in FIG. 5B, the distance L1 is 20 mm.
In this case, the film thickness difference T is very small, and the in-plane uniformity of the film thickness is greatly improved. It is considered that this is because the distribution region of the plasma P is not too large or too small, but is an appropriate distribution region.

A simulation was performed on the in-plane uniformity of the film thickness when the distance L1 was variously changed and the capacitance formed between the vicinity and the upper electrode 26 was changed. The results are also described. Here, the reason for performing the above simulation is as follows. First, it is considered that the factor affecting the distribution of the plasma P is related to the exposed portion of the mounting table 44 at the distance L1 and the dielectric constant of the member of the focus ring 66 corresponding to the distance L3. Here, for example, when the material of the mounting table 44 is AlN, the dielectric constant of the exposed portion of AlN is 7 to
9. The material of the focus ring 66 at the distance L3 is Al ₂
Assuming O _3, the dielectric constant of 8-10.

Generally, in a plasma state on a member having a high dielectric constant, since the capacitance is small, the voltage is high, a large amount of electric charge is generated, and the plasma is easily generated. On the other hand, in a plasma state on a member having a low dielectric constant, the capacitance is increased, so that the voltage is reduced, the charge is reduced, and the plasma is difficult to start.
The plasma state is not simply determined by the level of the dielectric constant of the member, but is further complicated by the surface area of the dielectric, the counter electrode, the shape of the processing chamber, and the like. Therefore, here, focusing on the dielectric constant of the dielectric, and the capacitance (capacitance) formed between the surface area of the dielectric and the counter electrode, the capacitance is roughly calculated by a simulation model. The uniformity of the distribution region of the plasma P (in-plane uniformity of the film thickness) and the sizes of the distances L1 and L3 were optimized.

FIGS. 6A and 6B show a model obtained by performing a simulation. The dimensions of each member are the same as the dimensions described in FIG. In addition, AlN (dielectric constant: ε = 8) is used as a member of the mounting table 44, and Al ₂ O ₃ is used as a material of the focus ring 66.
(Dielectric constant: ε = 9). 6, the capacitance formed between the area S1 of the exposed portion (the portion of the distance L1) of the mounting table 44 and the upper electrode 26 is C1, and the capacitance between the upper surface of the focus ring 66 and the upper electrode 26 is C1. The formed capacitance is C2. Here, generally, the capacitance C
Is given by the following equation. C = ε · S / d where ε is the dielectric constant of the dielectric, and S is the plane area of the dielectric (S
1, S2) and d are distances (L5, L7) between the showerhead and the dielectric.

FIG. 7 shows the result of the calculation model obtained by this simulation. Then, the ratio C1 / C2 of the two capacitances
FIG. 8 shows the relationship between the distance L1 and the in-plane uniformity of the film thickness, and FIG. 9 shows the relationship between the distance L1 and the ratio C1 / C2 of the two capacitances. FIG.
In order to keep the in-plane uniformity of the film thickness within 10%, it is better to set the ratio between the two capacitances to be within 10. For this purpose, FIG. It is found that setting the distance L1 to be within 27 mm is the best for keeping the distance L1 within the range. This is the same result as the case described above with reference to FIG. Here, the distance L1 is 10 m
Setting the value smaller than m is not preferable because the in-plane uniformity of the film thickness sharply increases as predicted from FIG. In the above embodiment, the mounting table 4 made of the first dielectric is used.
Although the focus ring 66 made of the fourth and second dielectrics is formed separately from each other, and the focus ring 66 is fitted to the periphery of the mounting table 44 as an example, the present invention is not limited to this. Alternatively, both members may be integrally formed of the same dielectric.

FIG. 10 is a partially enlarged view of the first modified example of the present invention. In this case, the inside of the upper surface of the cylindrical block-shaped dielectric is stepped in two steps and seated in a concave shape. As a result, the mounting table 44, the focus ring 66 and the mounting recess 6 are formed so as to have the same upper surface shape as shown in FIG.
8 are formed. Here, the outer peripheral side of the mounting concave portion 68 is raised one step to form a positioning step portion 82. In this case, the counterbore of the positioning step 82 is the focus ring 6.
6 is obtained.

FIG. 11 is a partially enlarged view of a second modification of the present invention. Here, as in the case of FIG. 10, the mounting table 44 and the focus ring 66 are integrally formed of the same dielectric. In this case, instead of the positioning step 82, a convex positioning projection 84 is formed to position the wafer. The positioning projection 84 is mounted on the mounting table 4.
4 may be formed in the shape of a ring along the circumferential direction, or may be provided at a plurality of discrete intervals, for example. Note that the positioning projection 84 may be employed in the example of the apparatus shown in FIG. FIG. 12 is a partially enlarged view of a third modification of the present invention, and FIG.
As in the case of 0, the mounting table 44 and the focus ring 66 are integrally formed of the same dielectric. in this case,
The positioning step 82 shown in FIG. 10 is not provided, and the upper surface on the inside of the mounting table 44 is a plane of completely the same level.
In this case, the counterbore amount is the thickness L of the focus ring 66.
It becomes 2.

In the above embodiment, a so-called parallel plate type plasma processing apparatus provided with an upper electrode and a lower electrode has been described as an example. However, the present invention is not limited to this, and an ICP using a spiral coil is used. Inductively Cou
Pled Plasma) type plasma processing apparatus, RI
E (Reactive Ion Etching) type plasma processing apparatus, ECR (Electron Cy)
Needless to say, the present invention can be applied to a plasma processing apparatus of a clotron resonance type.

Although the plasma CVD process has been described as an example of the plasma process, the present invention is not limited to this, and the present invention can be applied to other plasma processes such as a plasma etching process and a plasma ashing process. it can. Further, in the present embodiment, a semiconductor wafer has been described as an example of an object to be processed, but the present invention is not limited to this.
Of course, the present invention can be applied to the case of processing a D substrate, a glass substrate, and the like.

[0027]

As described above, according to the plasma processing apparatus of the present invention, the following excellent operational effects can be exhibited. According to the first to eighth, tenth, and eleventh aspects of the present invention, the distribution state of the plasma in the processing space in the processing container is optimized, and not only the in-plane uniformity of the plasma processing can be improved, but also the charge It is also possible to suppress the occurrence of up damage and improve the product yield. According to the ninth aspect of the present invention, since plasma CVD is performed as plasma processing, not only the in-plane uniformity of the deposited film can be improved by optimizing the plasma distribution state, but in this case, In addition, it is possible to suppress the occurrence of charge-up damage and improve the product yield.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a plasma processing apparatus according to the present invention.

FIG. 2 is a perspective view showing a focus ring.

FIG. 3 is a partially enlarged cross-sectional view of the plasma processing apparatus.

FIG. 4 is a graph showing a relationship between a distance L1 between an outer peripheral end surface of a wafer and an inner peripheral end surface of a focus ring and in-plane uniformity of a film thickness.

FIG. 5 is a diagram schematically illustrating a relationship between a plasma distribution state and a film thickness on a wafer when a distance L1 is variously changed.

FIG. 6 is a diagram showing a model when a simulation is performed.

FIG. 7 is a diagram showing a result of a calculation model by simulation.

FIG. 8 is a graph showing the relationship between the capacitance ratio C1 / C2 and the in-plane uniformity of the film thickness.

FIG. 9 is a graph showing a relationship between a distance L1 and a capacitance ratio C1 / C2.

FIG. 10 is a diagram showing a partially enlarged view of a first modified example of the present invention.

FIG. 11 is a diagram showing a partially enlarged view of a second modified example of the present invention.

FIG. 12 is a diagram showing a partially enlarged view of a third modified example of the present invention.

FIG. 13 is a schematic configuration diagram showing a conventional general plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 Plasma CVD film-forming apparatus (plasma processing apparatus) 22 Processing container 26 Shower head part (upper electrode) 28 Insulator 34 High frequency power supply 44 Mounting table (lower electrode) 46 Heater 50 Electrode main body 66 Focus ring 66A Inner peripheral end surface 68 Mounting Mounting recess 70 Outer peripheral end surface W Semiconductor wafer (workpiece)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G075 AA24 AA30 BC01 BC04 BC06 CA02 CA25 CA47 CA65 EB01 EC21 EE02 FB02 FB04 FC15 4K030 CA04 CA12 FA03 GA02 JA03 KA30 KA46 5F004 AA01 BA04 BB18 BB23 BB26 BB28 5F045 A03 DP05A05 EH06 EH13 EK07

Claims (11)

[Claims] Claims: 1. In a processing vessel made evacuable,
A plasma processing apparatus having a lower electrode also serving as a mounting table on which a target object is mounted, and an upper electrode, and applying a high-frequency voltage between the two electrodes to perform a plasma process on the target object. In the peripheral portion of the lower electrode, a focus ring is provided at a predetermined interval outside the outer peripheral end surface of the object to be processed, and the predetermined interval is set within a range of 10 to 27 mm. A plasma processing apparatus characterized in that: 2. The plasma processing apparatus according to claim 1, wherein said focus ring is made of an insulating material, and a thickness thereof is set in a range of 0.2 to 5 mm. 3. A plasma processing apparatus for performing plasma processing on an object to be processed in a processing chamber capable of being evacuated, comprising: an upper electrode; and a first dielectric for mounting the object to be processed. A mounting table serving also as a lower electrode, and an outer peripheral side of the mounting table, an annular focus ring made of a second dielectric material spaced a predetermined distance radially outward from an outer peripheral end of the object to be processed. A plasma processing apparatus characterized by comprising: 4. The plasma processing apparatus according to claim 3, wherein the focus ring is formed separately from the mounting table, and is fitted around an edge of the mounting table. 5. The mounting table and the focus ring,
4. The plasma processing apparatus according to claim 3, wherein the plasma processing apparatus is made of a dielectric having the same dielectric constant, and both are integrally formed. 6. The plasma processing apparatus according to claim 1, wherein the mounting table is provided with a convex positioning projection for positioning an outer peripheral end of the object to be processed. 7. The plasma processing apparatus according to claim 1, wherein the mounting table is provided with a positioning step for positioning an outer peripheral end of the object to be processed. 8. The plasma processing apparatus according to claim 1, wherein the upper electrode is also used as a shower head for introducing a predetermined gas into the processing chamber. 9. The plasma processing apparatus according to claim 1, wherein the plasma processing is a plasma CVD processing for depositing a thin film on a surface of the object. 10. The plasma processing apparatus according to claim 3, wherein the predetermined interval is in a range of 10 to 27 mm. 11. The plasma processing according to claim 3, wherein the dielectric constant of the first dielectric is set smaller than the dielectric constant of the second dielectric. apparatus.