JP2009260206A - Surface working method for discharge plasma processing apparatus, application electrode, and discharge plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface working method of a discharge plasma processing apparatus, an application electrode and a discharge plasma processing apparatus for achieving highly precise flattening by a one-time operation process, thereby improving the efficiency of working. <P>SOLUTION: Discharge plasma P forms hollow discharge plasma Ph and grow discharge plasma Pg. A processing face 14a of the substrate 14 is deeply dug by the hollow discharge plasma Ph formed at the central part of the discharge plasma P. In this case, the protrusion of the irregularities formed on a processing face 14a of the substrate 14 by digging by the hollow discharge plasma Ph is etched by glow discharge plasma Pg formed in the outer periphery of the hollow discharge plasma Ph so that the highly precise substrate is flattened. Also, the discharge plasma P simultaneously forms the hollow discharge plasma Ph and the glow discharge Pg, and the substrate 14 is synchronously etched. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface processing method, an applied electrode, and a discharge plasma processing apparatus for a discharge plasma processing apparatus.

  As a technique for planarizing a substrate such as a silicon wafer or a quartz wafer, mechanical polishing such as grinding or polishing and mechanical chemical polishing such as CMP are generally known. In addition, a technique for polishing a substrate by plasma has been established (for example, Patent Document 1).

  In general, when the surface of the substrate is further planarized after CMC polishing of the substrate, the surface of the substrate is planarized with high accuracy by performing plasma etching with a plasma processing apparatus. In particular, when surface treatment is performed to make the thickness of a very thin substrate uniform, the surface treatment by plasma etching is particularly effective because the substrate is not damaged.

  In Patent Document 1, in the plasma generator, when the entire surface of the substrate is planarized by plasma etching, the substrate to be surface-treated and the electrode for generating plasma are moved relative to each other. More specifically, as shown in FIGS. 6 and 7, the application electrode 50 is moved relative to the upper surface of the substrate 51 placed on the ground electrode (not shown) along the locus R in a zigzag manner. At this time, the application electrode 50 is moved in a zigzag manner while being shifted by the diameter r3 of the plasma P.

Then, after shifting by the diameter r3, the surface of the substrate 51 is exposed to plasma during the relative movement scanned in one direction, and the surface is plasma etched. Accordingly, since the plasma P is formed on the trajectory R along which the electrode 50 moves, the entire surface of the substrate 51 is plasma etched.
Japanese Patent Application Laid-Open No. 11-67736

  By the way, the substrate 51 that has been planarized by the above-described method has the following problems. FIG. 8 is a sectional view taken along line 10-10 of FIG. As shown in FIG. 8, the PV (Peak to Valley) value on the surface of the substrate 51 may not be suppressed. This is because, when the plasma used for etching in order to shorten the plasma processing time is a plasma having a high plasma density, it is locally deeply etched, but the boundary portion between the adjacent etching locations shifted by 1 pitch is It is not etched so deeply. As a result, the PV (Peak to Valley) value could not be reduced, so that the surface had to be flattened again by plasma etching with a plasma having a low plasma density, resulting in an increase in the number of work steps and poor work efficiency.

In addition, it is conceivable to perform planarization using plasma having a low plasma density from the beginning, but it takes a very long time to planarize one substrate, and the working efficiency is poor.
The present invention has been made to solve the above-described problems, and its purpose is to provide a surface of a discharge plasma processing apparatus that can achieve high-precision flattening and improve work efficiency in a single work process. A processing method, an applied electrode, and a discharge plasma processing apparatus are provided.

  The surface processing method of the discharge plasma processing apparatus of the present invention includes a ground electrode on which a substrate is placed and is electrically grounded, an application electrode that is spaced apart from the ground electrode, the ground electrode, and the application electrode Moving means for relatively moving, a high frequency voltage is applied between the ground electrode and the application electrode, and a plasma gas supplied between the application electrode and the substrate is caused by the action of the high frequency voltage. A surface processing method of a discharge plasma processing apparatus for generating discharge plasma by ionization and flattening a processing surface of the substrate by a reaction between the substrate and the discharge plasma, wherein the discharge plasma is etched in a central portion. A hollow discharge plasma having a high rate is formed, and a glow discharge plasma having an etching rate lower than that of the hollow discharge plasma is formed on the outer periphery of the hollow discharge plasma. And, it processed planarizing the treated surface.

  According to the surface processing method of the discharge plasma processing apparatus of the present invention, the surface of the substrate is deeply processed by hollow discharge plasma having a high etching rate formed at the center of the discharge plasma. At this time, the unevenness of the processing surface of the substrate formed due to the deep processing by the hollow discharge plasma is etched by the low discharge rate glow discharge plasma formed on the outer peripheral portion of the hollow discharge plasma. An accurate substrate can be planarized.

  In addition, since the discharge plasma is formed of a hollow discharge plasma and a hollow discharge plasma at the same time and the substrate is etched at the same time, it is possible to manufacture a substrate that is planarized with high accuracy in a short time.

  In this surface processing method, the application electrode and the substrate are relatively moved so that the application electrode moves in a zigzag manner on the processing surface of the substrate at a predetermined pitch to etch the processing surface of the substrate. You may let them.

  According to this surface processing method, the processed surface of the substrate can be efficiently and uniformly processed by zigzag movement, and the unevenness of the processed surface of the substrate based on the deep processing of the hollow discharge plasma is also uneven by the glow discharge plasma. Since etching is performed, a highly accurate substrate can be planarized.

In this surface processing method, the predetermined pitch may be a diameter of the hollow discharge plasma formed in a central portion of the discharge plasma.
According to this surface processing method, hollow discharge plasma deep processing is performed uniformly on the processing surface of the substrate, so that a highly flat substrate with no processing unevenness can be manufactured in a short time. .

  The application electrode of the present invention is an application electrode that generates a discharge plasma on a processing surface of a substrate placed on a ground electrode when a high-frequency voltage is applied, and has a through hole formed in a direction toward the ground electrode. And an insulator having a through-hole formed through the through-hole communicating with the through-hole formed in the electrode portion.

  According to the application electrode of the present invention, when a high frequency voltage is applied between the electrode portion and the ground electrode, glow discharge occurs at the tip surface portion of the electrode portion (insulator) facing the substrate. On the other hand, since the center part of the tip of the electrode part is covered with an insulator and has a through hole, hollow discharge occurs when a high-frequency voltage is applied between the electrode part and the ground electrode.

  Accordingly, a single discharge electrode can simultaneously generate a hollow discharge plasma having a high etching rate at the center and a glow discharge plasma having a low etching rate so as to surround the hollow discharge plasma at the outer periphery.

  The discharge plasma processing apparatus according to the present invention includes a ground electrode on which a substrate is placed and is electrically grounded, an application electrode that is spaced from and opposed to the ground electrode, and the ground electrode and the application electrode are relative to each other. A moving means for moving, applying a high frequency voltage between the ground electrode and the application electrode, and ionizing plasma gas supplied between the application electrode and the substrate by the action of the high frequency voltage. A discharge plasma processing apparatus for generating discharge plasma and flattening a processing surface of the substrate by a reaction between the substrate and the discharge plasma, wherein the application electrode is formed of the application electrode.

  According to the discharge plasma processing apparatus of the present invention, it is possible to simultaneously form a hollow discharge plasma having a high etching rate at the center and a glow discharge plasma having a low etching rate at the outer periphery of the hollow discharge plasma. Therefore, a substrate that is planarized with high accuracy can be manufactured.

Hereinafter, an embodiment in which a surface processing method of a discharge plasma processing apparatus of the present invention is embodied will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of an essential part for explaining a discharge plasma processing apparatus 10. In the discharge plasma processing apparatus 10, an XY direction moving device 12 as a moving unit is provided on a bottom surface 11 a of a processing chamber 11, and an electrode stage 13 is connected and fixed to a working arm 12 a of the XY direction moving device 12 as a ground electrode. .

  The XY direction moving device 12 moves the electrode stage 13 in the X direction (left and right direction in FIG. 1) as the main scanning direction via the operating arm 12a, and Y as the sub scanning direction perpendicular to the X direction. It is made to move in the direction (perpendicular to the paper surface in FIG. 1).

  The electrode stage 13 is formed of stainless steel. The electrode stage 13 has a substrate 14 placed on its placement surface 13a. Accordingly, the substrate 14 placed on the electrode stage 13 is moved and guided in the X and Y directions in the processing chamber 11. Examples of the substrate 14 include a material containing a component that reacts with active atoms (radicals) contained in plasma to vaporize a reactant. In this embodiment, for example, a silicon (Si) substrate is used.

  A support device 15 is provided on the upper surface in the processing chamber 11, and an application electrode 20 is disposed on the lower surface of the support device 15 toward the lower electrode stage 13. As shown in FIG. 2, the application electrode 20 has an electrode body 21 made of stainless steel and an insulator 22 made of alumina.

  The electrode body 21 has a cylindrical body and is fixed to the support device 15. The electrode body 21 has a first through hole 21a formed therethrough along its central axis. An insulator 22 is fixed to the lower surface as the facing surface of the electrode body 21. The insulator 22 has a disk shape, and a second through hole 22a communicating with the first through hole 21a formed in the electrode body 21 is formed through the center of the insulator 22. Accordingly, the lower surface of the electrode main body 21 is covered with the insulator 22.

  The height adjustment of the application electrode 20 supported by the support device 15, that is, the adjustment of the distance between the insulator 22 and the substrate 14 placed on the electrode stage 13 is performed by adjusting the height provided in the support device 15. It is adjusted by the mechanism.

  Further, the support device 15 is provided with a plasma gas supply path (not shown) that communicates with the first through hole 21a of the application electrode 20 (electrode body 21), and the plasma gas G supplied from outside the processing chamber 11 is supplied to the support device 15 through the first through hole 21a. 1 to the through hole 21a. The plasma gas G introduced into the first through hole 21 a is discharged toward the substrate 14 from the second through hole 22 a of the insulator 22. Therefore, a passage through which the plasma gas G flows is formed by the first through hole 21a and the second through hole 22a.

  Here, the plasma gas G is a gas that generates plasma P by dissociation of contained gas molecules by the action of a high-frequency voltage (the action of an electric field). For example, helium (He) gas or Ar (argon) gas is used. Such a mixed gas of a carrier gas and a processing gas. The processing gas varies depending on the constituent material of the substrate 14 to be etched. When the constituent material of the substrate 14 is the aforementioned silicon compound, a fluorine-based gas such as CF4, CHF3, C2F6, SF6, a chlorine gas such as CCl4, or the like is used.

  A power supply circuit 25 is connected between the application electrode 20 (electrode body 21) and the electrode stage 13. The power supply circuit 25 applies a high-frequency voltage between the electrode body 21 and the electrode stage 13 to induce an electric field whose direction is reversed at a high frequency in the gap between the application electrode 20 and the electrode stage 13. ing.

  When an electric field whose direction is reversed at a high frequency is induced between the application electrode 20 and the electrode stage 13, the molecules of the plasma gas G existing between the substrate 14 and the application electrode 20 are ionized, and the discharge plasma P Will occur.

  At this time, the generated discharge plasma P generates different discharge plasmas depending on the position. More specifically, glow discharge occurs on the lower surface of the application electrode 20 (the lower surface portion of the insulator 2). However, since a central portion of the application electrode 20 has an opening (through hole 22a), hollow discharge occurs. Occur.

  As a result, as shown in FIG. 3, the central portion of the application electrode 20 (the through-hole 22a portion of the insulator 22) forms a hollow discharge plasma Ph having a high etching rate by hollow discharge. A glow discharge plasma Pg having an etching rate lower than that of the hollow discharge plasma Ph is formed on the outer peripheral portion of the hollow discharge plasma Ph (the lower surface portion of the insulator 22). That is, the application electrode 20 forms a high rate etching region Z1 etched by the hollow discharge plasma Ph having a high etching rate at the center, and forms a low rate etching region Z2 so as to surround the high rate etching region Z1. To do.

Next, a method for flattening the processing surface 14a of the substrate 14 using the plasma processing apparatus 10 will be described.
Now, as shown in FIGS. 1 and 2, the substrate 14 is placed on the placement surface 13 a of the electrode stage 13. Then, the XY direction moving device 12 is driven to make a relative movement along the locus R from the start point P1 to the end point P2 indicated by a broken line in FIG. The electrode stage 13 is operated so as to move.

  That is, the application electrode 20 starts moving in the X direction from the starting point P1 on the substrate 14. When the end of the substrate 14 is reached, the movement of the application electrode 20 in the X direction is stopped, and then the application electrode 20 is moved in the Y direction by the diameter r1 of the hollow discharge plasma Ph. Next, the movement of the application electrode 20 in the anti-X direction is started, and when the application electrode 20 reaches the end of the substrate 14, the movement of the application electrode 20 in the anti-X direction is stopped. Subsequently, after the applied electrode 20 is moved in the Y direction by the diameter r1 of the hollow discharge plasma Ph, the substrate 14 is started to move in the X direction. Thereafter, the same process is repeated, and the application electrode 20 is relatively moved to the end point P2.

  At this time, the processing surface 14a of the substrate 14 passes uniformly upward by moving in a Zigzag manner in the X direction and the anti-X direction while moving in the Y direction at a pitch of the diameter r1 of the hollow discharge plasma Ph. When facing the applied electrode 20, the high-rate etching region Z1 is entered, exposed to the hollow discharge plasma Ph, and etched at a high etching rate. At this time, the periphery enters the low-rate etching region Z2 and is exposed to the glow discharge plasma Pg.

  As a result, the center position etched by the hollow discharge plasma Ph is etched deeper, but the boundary portion between the adjacent one-pitch shifted etching portions is not etched so deeply, but the glow discharge existing around the hollow discharge plasma Ph is present. The portion where the plasma Pg is not etched deeply to compensate for this is etched.

  More specifically, a portion that is not deeply etched during the movement in the previous anti-X direction before moving in the X direction and the next movement in the anti-X direction after moving in the X direction is a hollow discharge plasma. Ph passes through and is etched.

  As shown in FIG. 5, the etching of the hollow discharge plasma Ph can reduce the difference between the deeply etched portion and the portion that is not deeply etched, that is, the PV (Peak to Valley) value can be reduced. The processing surface 14a is flattened.

Next, effects of the embodiment configured as described above will be described below.
(1) According to the above embodiment, the discharge plasma P forms the hollow discharge plasma Ph and the glow discharge plasma Pg, and the substrate 14 is formed by the hollow discharge plasma Ph formed at the center of the discharge plasma P and having a high etching rate. The processed surface 14a is deeply drilled. At this time, the unevenness of the processing surface 14a of the substrate 14 formed by deep drilling using the hollow discharge plasma Ph is etched, and the projection 2 is etched by the glow discharge plasma Pg formed at the outer periphery of the hollow discharge plasma Ph and having a low etching rate. To do. Therefore, a highly accurate substrate can be planarized.

  (2) According to the above embodiment, the discharge plasma P forms the hollow discharge plasma Ph and the glow discharge plasma Pg at the same time, and etches the substrate 14 at the same time. Can be manufactured.

  (3) According to the above embodiment, the application electrode 20 moves on the processing surface 14a of the substrate 14 in a zigzag manner to etch the processing surface 14a of the substrate 14, so that the substrate can be efficiently and uniformly applied. The 14 processed surfaces 14a can be processed.

In addition, since the pitch of the zigzag movement is the diameter of the hollow discharge plasma Ph, it is possible to manufacture a substrate flattened with high accuracy without processing unevenness in a short time.
(4) According to the above embodiment, the electrode body 21 of the application electrode 20 has the first through hole 21a, and the lower surface excluding the first through hole 21a is covered with the insulator 22. Therefore, when a high frequency voltage is applied between the electrode portion and the ground electrode, glow discharge is caused at the tip surface (lower surface of the insulator 22) portion of the electrode portion (insulator) facing the substrate, and the cylindrical electrode portion Hollow discharge can occur at the center of the tip (through hole 22a of insulator 22).

In addition, you may change the said embodiment as follows.
In the above embodiment, the thickness (diameter r1) of the hollow discharge plasma Ph and the thickness (diameter r2) of the glow discharge plasma Pg are not particularly limited, but the glow discharge plasma Pg is formed around the hollow discharge plasma Ph. For example, when the diameter r1 of the hollow discharge plasma Ph is 2 mm, for example, the glow discharge plasma Pg having a diameter r2 of 3 mm to 7 mm may be formed.

Schematic for demonstrating a plasma processing apparatus. The principal part sectional drawing for demonstrating a plasma processing apparatus. Explanatory drawing explaining hollow discharge plasma and hollow discharge plasma. The figure which shows the relative movement locus | trajectory of the discharge electrode with respect to a board | substrate. Sectional drawing which shows the surface of the board | substrate planarized by discharge plasma. The schematic diagram of the board | substrate which is planarized with the conventional discharge plasma. The figure which shows the relative movement locus | trajectory of the discharge electrode with respect to the board | substrate for demonstrating the conventional planarization process process. Sectional drawing which shows the surface of the board | substrate planarized by the conventional discharge plasma.

Explanation of symbols

  G ... Plasma gas, P ... Discharge plasma, Ph ... Hollow discharge plasma, Pg ... Glow discharge plasma, R ... Relative movement trajectory, r1, r2 ... Diameter, 10 ... Plasma processing device, 12 ... XY direction moving device, 13 ... Electrode Stage 14, substrate 14 a, processing surface 20, applied electrode 21, electrode body 21 a, first through hole 22, insulator 22 a, second through hole 25, power supply circuit

Claims (5)

A ground electrode on which the substrate is placed and electrically grounded;
An application electrode spaced apart from the ground electrode;
Moving means for relatively moving the ground electrode and the application electrode;
A high-frequency voltage is applied between the ground electrode and the application electrode, and a plasma gas supplied between the application electrode and the substrate is ionized by the action of the high-frequency voltage to generate discharge plasma, and the substrate And a surface processing method of a discharge plasma processing apparatus for flattening a processing surface of the substrate by reaction with the discharge plasma,
The discharge plasma is formed in the center with a hollow discharge plasma having a high etching rate, and the glow discharge plasma having a lower etching rate than the hollow discharge plasma is formed in the outer periphery of the hollow discharge plasma to flatten the processing surface. A surface processing method of a discharge plasma processing apparatus, characterized by processing. In the surface processing method of the discharge plasma processing apparatus of Claim 1,
The application electrode is moved in a zigzag manner at a predetermined pitch on the processing surface of the substrate, and the application electrode and the substrate are relatively moved so as to etch the processing surface of the substrate. A surface processing method of a discharge plasma processing apparatus. In the surface processing method of the discharge plasma processing apparatus according to claim 2,
The surface processing method for a discharge plasma processing apparatus, wherein the predetermined pitch is a diameter of the hollow discharge plasma formed in a central portion of the discharge plasma. An application electrode to which a high frequency voltage is applied to generate discharge plasma on the processing surface of the substrate placed on the ground electrode,
An electrode part having a through-hole formed in a direction toward the ground electrode;
An application electrode comprising: an insulating body that covers the surface of the electrode portion facing the ground electrode with an insulating coating and has a through hole that communicates with a through hole formed in the electrode portion. A ground electrode on which the substrate is placed and electrically grounded;
An application electrode disposed opposite the ground electrode;
Moving means for relatively moving the ground electrode and the application electrode;
A high-frequency voltage is applied between the ground electrode and the application electrode, and a plasma gas supplied between the application electrode and the substrate is ionized by the action of the high-frequency voltage to generate discharge plasma, and the substrate And a discharge plasma processing apparatus for flattening the processing surface of the substrate by reaction with the discharge plasma,
A discharge plasma processing apparatus, wherein the application electrode is formed of the application electrode according to claim 4.

Images