JP4399396B2 - Mounting table - Google Patents

Description

  The present invention relates to a stage for placing a substrate such as glass to be plasma-treated.

  As a mounting table for a substrate to be plasma-processed, Patent Document 1 below discloses that a first dielectric plate is provided on the upper surface of a mounting table main body via an O-ring, and a heater is embedded on the first dielectric plate. Two dielectric plates are provided, the surface of the first dielectric plate is processed to be uneven, and a gap is formed between the second dielectric plate and the second dielectric plate. Thus, a vacuum processing apparatus is described in which alteration of the O-ring due to heat is suppressed.

  Patent Document 2 below includes a susceptor having a surface for mounting a semiconductor substrate, a heating block installed below the susceptor, and an elastic clip member for joining the heating block and the susceptor. Thus, a semiconductor substrate holding device is described in which a gap exists between the front surface of the heater block and the back surface of the susceptor so that the temperature distribution of the semiconductor substrate can be made uniform.

Japanese Patent Laid-Open No. 10-223621 JP 2000-133698 A

  As a requirement of the plasma apparatus for plasma processing the substrate, as shown in the right side of FIG. 4, plasma heat is generated on the substrate 41 of the mounting table (hereinafter also referred to as “stage”) at the same time as the plasma ignition. In order to stabilize the heat input, it is necessary to correct the heat input during the process.

  Thus, in order to control the stage temperature at a constant level, the heat removal from the heater to the lower surface of the stage is always kept constant in the plane, and as shown on the left side of FIG. 4, during the plasma heat input (for example, 2145 W) For example, it is necessary to reduce the power of the heater 42 in the heater block 14 from 25000 W to 22855 W, for example, to equalize the plasma heat input and the heat removal from the heater to compensate for temperature fluctuations.

  FIG. 4 is a time chart for controlling the stage temperature to be constant. The stage setting temperature is made constant, and the substrate temperature is set as the process temperature at the time of plasma ignition. At the time of plasma ignition, if the heater heat input corresponding to the plasma heat input is lowered so that the plasma heat input and the heater heat release are equivalent, the stage set temperature is made constant.

  Therefore, in-plane uniform heat removal is performed in order to make plasma heat input and heater heat removal equivalent. FIG. 5 is a view showing an example in which a thermal insulator 13 is interposed between the heater block 14 and the mounting table body 12. In order to perform uniform in-plane heat removal by the heat insulator 13, It is necessary that the thermal resistance is always uniform in the plane regardless of the heat input conditions and the environment. Of course, even when the thermal insulator 13 is not interposed, it is necessary that the heat input conditions for heat removal are always uniform.

  In order to stabilize this thermal resistance, the following conditions (1), (2) and (3) are necessary. (1) Stabilization of contact thermal resistance (for example, constant contact rate and constant contact load), (2) Stabilization of gas heat transfer rate (for example, constant gas pressure and in-plane distance between transmission surfaces) (3) Stabilization of thermal radiation (for example, the surface state (emissivity) of the transmission surface is constant within the surface).

  In FIG. 5, in order to satisfy the above condition, the contact surface with the thermal insulator 13 supporting the heater block 14 is fixed so as not to float, and the distance between the heater block 14 and the mounting table body 12 ( (Hereinafter also referred to as “space”), it is necessary to fix so that it does not change.

  However, since various materials are used as the constituent members of the heater block 14, the heater block 14 contracts and expands freely between materials due to the difference in thermal expansion coefficient of the materials at high temperatures. It moves by contraction and expansion.

  FIG. 6 is a diagram showing an example in which the heater block 14 on the mounting table main body 12 fixed to the support portion 11 is restrained by the outer periphery clamp 61. When there is plasma heat input, the heater block 14 is shown in FIG. As shown in (b) to (b), it becomes convex due to thermal expansion, and in-plane non-uniformity occurs at the heat transfer coefficient interface. In addition,

  FIG. 7 is a diagram showing an example in which the heater block 14 on the spacer 22 arranged on the mounting table main body 12 is a self-supporting type. In this case, too, the thermal expansion of the heater block, the thermal expansion of the mounting table main body, etc. As a result, the relative position of the mounting table moves indefinitely.

  Thus, as a support function of the heater block, in order to stabilize the contact portion, a support function that restrains the heater block in the space direction and can freely move in the direction of thermal expansion is required.

  The present invention relates to a stage structure of a plasma processing apparatus, and in particular, in a heater support structure, a direction in which a heater is held and fixed at a certain load or more with respect to the direction of heat flux of plasma heat input and moved by thermal expansion of the heater ( The heater is fixed by an elastic body so that it can move freely in the direction perpendicular to the heat flux.

  By making plasma heat input and heater heat removal equivalent in the plane, it is possible to perform a uniform plasma process in the plane, and in particular, it is possible to perform a uniform plasma process on a large substrate.

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

  FIG. 1 is a schematic configuration diagram of a mounting table 10 according to the present invention, and FIG. 1 (b) is an enlarged view of a portion shown in a circle of FIG. 1 (a). A mounting base body 12 fixed to the support portion 11, and a thermal insulator 13 and a heater block 14 are sequentially disposed on the mounting base body 12.

  The thermal insulator 13 is provided with a plurality of through holes 15, and through the through holes 15, the tip ends of the bolts 17 are fixed to the screw holes 16 provided in the heater block. The mounting table main body 12 is also provided with openings 18 corresponding to the plurality of through holes 15, and bolts 17 are passed through the through holes 15 and the openings 18.

  A coil spring 19 is interposed between the head of the bolt 17 and the mounting table body 12, and the coil spring 19 is accommodated in a spring receiving groove 20 provided in the mounting table body 12.

  In FIG. 1, the coil spring 19 is compressed by screwing a bolt 17, and the heater block 14, the thermal insulator 13, and the mounting table body 12 are elastically held by a spring force repelling the compression. Become.

The mounting table main body 12 and the thermal insulator 13 are provided with spacer receiving grooves 21, and the spacers 22 are placed here. The spacer 22 keeps the mounting table main body 12, the thermal insulator 13, and the heater block 14 at a predetermined interval (space). Further, here, the heat insulator 13 are arranged one, if necessary, in order to ensure the temperature gradient of the table body 12 mounting a heater block 14, placing several sheets double through the spacer 22 Can do.

  FIG. 2 is a diagram illustrating an example of the case where the heater block 14 is thermally expanded and moves left and right during plasma heat input. FIG. 2A illustrates the case where the heater block 14 moves to the left. ) Is when moved to the right.

  As shown in FIG. 2, the heater block 14 is held at a constant load in the direction of the heat flux of the plasma heat input (vertical direction in the figure) by the spring force of the coil spring 19, and the heat flow using the twist of the coil spring 19 The bundle can move freely in a right angle direction (horizontal direction in the figure).

  As described above, by maintaining a constant space between the mounting table main body 12 and the heater block 14, highly reliable plasma processing can be performed. Although the case where the heater block 14 moves is described here, the same can be said when both the heater block 14 and the mounting table body 12 move in the horizontal direction.

  FIG. 3 shows a rubber ring 31 in place of the coil spring 19 shown in FIG. 1, and the rubber ring 31 housed in the rubber ring receiving groove 32 also has the heater block 14 attached to the rubber ring 31 in the same manner as the coil spring 19. The heater block 14 is held at a constant load in the vertical direction so that the heater block 14 can move freely in the horizontal direction. The same applies to the case where both the heater block 14 and the mounting table body 12 move in the horizontal direction.

Schematic configuration diagram of a mounting table according to the present invention The figure which shows the example in case the heater block shown in FIG. 1 expands thermally, and moves to right and left The figure which shows the example which replaced with the coil spring shown in FIG. 1, and was made into the rubber ring. Time chart for controlling stage temperature at a constant level The figure which shows the case where a thermal insulator is interposed between a heater block and a mounting base main body. The figure which shows the example which restrained the heater block with the outer periphery clamp The figure which shows the example in which a heater block is self-supporting

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Mounting stand (stage), 11 ... Support part, 12 ... Mounting stand main body, 13 ... Thermal insulator, 14 ... Heater block, 15 ... Through-hole, 16 ... Screw hole, 17 ... Bolt, 18 ... Opening hole, 19 ... Coil spring, 20 ... spring receiving groove, 21 ... spacer receiving groove, 22 ... spacer, 31 ... rubber ring, 32 ... rubber ring receiving groove, 41 ... substrate, 42 ... heater, 61 ... outer periphery clamp

Claims (3)

In the mounting table main body fixed to the support member, and the mounting table of the substrate to be plasma processed, comprising a heater block disposed on the mounting table main body,
A plurality of bolts connecting the table body and the heater block,
A thermal insulator provided between the mounting table main body and the heater block;
A spacer placed between the mounting table main body and a spacer receiving groove provided in each of the thermal insulators;
Tip of the bolt into the threaded hole formed in the heater block is fixed through the through hole formed in the heat insulator and an opening provided in the mounting table body, and the opening of the mounting table main body and the head of the bolt and an elastic body interposed between,
Said elastic body includes a feature that holds the heater block at a constant load to the plasma heat input way direction, the heater block and the thermally expanded freely plasma heat input way direction a direction to move the perpendicular direction The mounting table.   The mounting table according to claim 1, wherein the elastic body is a coil spring.   The mounting table according to claim 1, wherein the elastic body is a rubber ring.