JP2913666B2 - Sample holding device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample holding device, and more particularly, to a case where a sample which is composed of an insulator layer and a sample stage and is heated by irradiation with plasma or the like and which becomes high in temperature is held. The present invention relates to a sample holding device used for, for example, a plasma CVD device.

2. Description of the Related Art Semiconductor manufacturing equipment using plasma, for example, plasma CV
The sample holding device provided in the D device or the like includes a sample stage cooled by a coolant and an insulator layer.

For example, electron cyclotron resonance (E lectron C yclo
The ECR plasma is generated by using the tron R esonance), allowed to form a thin film of a desired material on the surface of the sample
A sample holding apparatus used in the manufacture of a semiconductor integrated circuit such as a CVD (Chemical Vapor Deposition) apparatus or a dry etching apparatus for forming a fine circuit pattern on the surface of a sample will be described with reference to FIG.
In this sample holding device, a sample stage 11 is attached to a base 10, and a flow channel 12 for circulating a coolant is provided in the sample stage 11.
Are formed. An inlet pipe 13 and an outlet pipe 14 are connected to the flow path 12, and the cooling liquid is discharged from the inlet pipe 13 through the flow path 12 to the outlet pipe 14.
On the left side of the sample table 11 in the figure, an insulator layer 15 is fixed via a heat conductor 16 such as silicon rubber, and the sample 17 is electrostatically chucked on the left side of the insulator layer 15. It has become. The insulator layer 15 is formed in a manner that an electrode layer 19 is buried inside an insulator 18 made of, for example, ceramic, and the electrode layer 19 penetrates through the base 10 and the sample stand 11 to form an electrode rod. 20 are connected. An insulating cylinder 21 is interposed in a portion of the base 10 and the sample base 11 through which the electrode rod 20 passes.

The insulating layer 15 is fixed to the sample table 11 by a flange 22 and an electrode holder 23 formed on the outer peripheral surface on the right side of the insulating layer 15.
The electrode holder 23 is bolted to the sample stage 11 by joining with the flange portion 24 formed on the inner peripheral surface of the left side surface of the sample (not shown).
It is done by being done.

When plasma is applied to the sample 17 electrostatically chucked by the sample holding device configured as described above, the temperature of the sample 17 rises.

Therefore, conventionally, in order to control the temperature of the sample 17, the sample stage 11 is cooled by flowing a coolant such as water or antifreeze from the inlet tube 13 and discharging the coolant from the outlet tube 14 through the flow channel 12. Was. In addition, a heat transfer body 16 made of silicon rubber or silicon-based grease is interposed between the insulator layer 15 and the sample stage 11 to reduce the increase in the contact heat transfer area, which is extremely small in the case of contact between rigid bodies. The aim was to improve the cooling capacity.

In addition, there is a method of filling He gas as a heat conductor in order to increase heat transfer between the insulator layer 15 and the sample stage 11.

Problems to be Solved by the Invention However, as described above, in the conventional sample holding device, although the heat transfer member 16 is interposed in the heat transfer between the sample stage 11 and the insulator layer 15, When silicon rubber is used as the heat transfer body 16, the insulating layer 15 cannot be sufficiently cooled because of poor adhesion such as a gap between the silicon rubber and the insulating layer 15 or the sample stage 11.

When He gas is used as the heat transfer body, there is a possibility that discharge occurs between the insulator layer 15 and the sample stage 11. In order to further enhance the heat transfer effect of He gas, the insulator layer 15
It is necessary that the gap between the sample and the sample table 11 be 0.5 mm or less, but it is difficult to keep the entire surface uniformly 0.5 mm or less.

Therefore, a sufficient cooling effect of Sample 17 could not be obtained.

For this reason, the following various problems have occurred.
For example, a rise in temperature during ECR etching causes deformation or alteration of the etching resist, and also adversely affects the etched shape. Further, a rise in temperature during the formation of the insulating film by the ECR-CVD method causes the aluminum wiring already formed on the semiconductor substrate to be damaged or burned, which has been a cause of stress migration of the semiconductor substrate.

When a silicon-based grease is used as the heat transfer member 16, the grease deteriorates with time and the cooling capacity decreases with time, or the grease is removed from the sample table 11 and the insulator layer.
There was a problem that the sample 17 was oozed out from the area 15 and contaminated the sample 17.

The present invention has been devised in view of the above problems, and has an improved cooling capability for a sample held by an insulator layer 15 and a sample holding device capable of easily maintaining and controlling a sample temperature at a low temperature. For example, high integration of LSI,
An object is to facilitate miniaturization.

Means for Solving the Problems In order to achieve the above-mentioned object, a sample holding device according to a first invention of the present invention is a sample holding device including an insulator layer and a sample stage, wherein the insulator layer and the It is characterized in that a flexible metal sheet is interposed between the sample table and the sample table so that both surfaces thereof are in close contact with each other.

Further, a sample holding device according to a second invention of the present invention is a sample holding device provided with an insulator layer and a sample stage, wherein both surfaces of the insulator layer and the sample stage are brought into close contact with each other. A flexible organic composite sheet containing thermal conductive fibers is interposed.

Function According to the above-described configuration, a flexible metal sheet is interposed between the insulator layer and the sample table constituting the sample holding device, with both surfaces of the flexible metal sheet being in close contact with the insulator layer and the sample table. I have. Therefore, the insulator layer and the sample stage are buried without gaps by the metal sheet, and the contact area is increased, and at the same time, the good thermal conductivity of the metal sheet is effectively used. The heat transfer to the sample is performed smoothly, and the cooling capacity for the sample held by the insulator layer is also improved.

Further, even if an organic composite material sheet containing flexible carbon or metal whiskers is interposed between the insulator layer and the sample stage that constitute the sample holding device, the flexible metal sheet is interposed. As in the case of mounting, the good thermal conductivity of the metal whiskers contained in the organic composite material sheet can be effectively used, and the heat transfer from the insulator layer to the sample stage is performed smoothly, The cooling capacity for the sample held on the insulator layer is improved.

Embodiment Hereinafter, an embodiment of a sample holding device according to the present invention will be described with reference to the drawings.

Note that components having the same functions as the components in the conventional example are denoted by the same reference numerals.

FIG. 1 is a vertical sectional view of a plasma CVD apparatus provided with a sample holding device 30 according to the present embodiment. 35 is a plasma generation chamber, 36 is a waveguide, 37 is a reaction chamber for depositing a thin film on the sample 17, and 38 is an excitation coil. The plasma generation chamber 35 is made of stainless steel, is formed so as to form a cavity resonator for microwaves, and has a microwave introduction window 40 closed by a quartz glass plate 39 at the center of one side wall. Is formed, and a microwave introduction window 40 is provided at the center of the other side wall.
, A plasma extraction window 41 is formed.
One end of the waveguide 36 is connected to the microwave introduction window 40,
Also, this plasma drawer window 41 is
A reaction chamber 37 facing 41 is connected, and further around the plasma generation chamber 35 and the one end of a waveguide 36 connected to the plasma generation chamber 35, these plasma generation chamber 35 and the waveguide 36 An excitation coil 38 is provided concentrically.

The other end of the waveguide 36, which is not connected to the microwave introduction window 40, is connected to a high-frequency oscillator (not shown). Microwaves emitted from this high-frequency oscillator generate plasma through the microwave introduction window 40. It is configured to be introduced into the chamber 35.

The excitation coil 38 is connected to a DC power supply (not shown). When a microwave is introduced into the plasma generation chamber 35 by applying a current to the DC power supply, a magnetic field is generated so as to generate plasma. At the same time, a divergent magnetic field whose magnetic flux density decreases toward the reaction chamber 37 is formed, and the plasma generated in the plasma generation chamber 35 is introduced into the reaction chamber 37.

The reaction chamber 37 has an exhaust port 42 connected to an exhaust device (not shown) on the side wall, and a sample holding device 30 is disposed inside the reaction chamber 37 so as to face the plasma extraction window 41. The sample 17 is detachably mounted on the front surface of the apparatus 30 so as to face the plasma extraction window 41 by an electrostatic chuck method.

Here, the sample holding device 30 will be described in detail with reference to FIG. 2. The sample holding device 30 is provided with a sample base 11 attached to a base 10 and a flow for circulating a cooling liquid. A path 12 is formed. An inlet pipe 13 and an outlet pipe 14 are connected to the flow path 12, and the coolant flows from the inlet pipe 13 to the flow path 12.
It is configured to be discharged from the outlet pipe 14 through 12. On the left side of the sample table 11 in the figure, an insulator layer 15 is fixed via a metal sheet made of Injum (In) as a heat conductor 16, and a sample 17 is placed on the left side of the insulator layer 15. It can be held. The insulator layer 15 is formed, for example, with an electrode layer 19 buried inside an insulator 18 made of, for example, ceramic, and the electrode layer 19 penetrates the base 10 and the sample base 11 and has an electrode rod. 20 are connected. An insulating cylinder 21 is interposed at a portion where the electrode rod 20 penetrates the base 10 and the sample table 11. Also, a DC power supply is
43 and a high frequency power supply 44 are connected (FIG. 1).

The insulating layer 15 is fixed to the sample table 11 by a flange 22 and an electrode holder 23 formed on the outer peripheral surface on the right side of the insulating layer 15.
The electrode holder 23 is bolted (not shown) to the sample stage 11 by bonding with a flange portion 24 formed on the inner peripheral surface on the left side of the sample.

Therefore, in such a plasma CVD apparatus,
The sample 17 is mounted on the sample holding device 30 in the reaction chamber 37, and the inside of the plasma generation chamber 35 and the reaction chamber 37 is set to a required degree of vacuum, and then the plasma is supplied through the gas supply pipe 45, the gas supply pipe 46, and the annular nozzle 47. The same or different reaction gas (or inert gas) is supplied into the generation chamber 35 and the reaction chamber 37, respectively, and a direct current is supplied to the exciting coil 38, and the waveguide 36,
When microwaves are introduced into the plasma generation chamber 35 through the microwave introduction window 40, the microwaves enter a resonance state in the plasma generation chamber 35 functioning as a plasma cavity resonator, decompose the reaction gas, and excite the plasma by resonance excitation. Is generated. The ions in the generated plasma are irradiated to the sample holder 30 as an ion beam having a direction along the divergent magnetic field formed by the exciting coil 38, and the thin film is applied to the sample 17 mounted on the sample holder 30. To form

In this case, the amount of heat applied to the sample holding device 30 and the sample 17 has a close relationship with the ion current in the plasma, and the temperatures of the sample holding device 30 and the sample 17 rise. For this reason, in the conventional sample holding device 30, the flow path 12 for circulating the cooling liquid through the sample stage 11 for cooling is formed, and heat conduction between the sample stage 11 and the insulator 18 is utilized. Silicon-based rubber or silicon-based grease was interposed as the heat transfer body 16 for cooling. However, when a silicon-based rubber is used, the adhesion between the silicon rubber and the insulator 18 or between the silicone rubber and the sample stage 11 is poor, and a gap is formed between the sample stage 11 and the insulator 18. The contact area becomes small, and the desired cooling effect cannot be obtained as shown by the curve (c) in FIG. Further, when a rubber-based material is used as the heat transfer member 16, the heat transfer / cooling effect is also reduced with time due to the deterioration of the material itself with time.

Further, when silicon-based grease or the like is used, the grease deteriorates with time, similarly to silicon-based rubber or the like, so that the cooling effect deteriorates with time. In addition, when grease or the like is used, grease or the like may leak from between the sample table 11 and the insulator 18 and contaminate the sample 17. On the other hand, in the sample holding device 30 according to the present embodiment,
A metal sheet made of Injum (In) is used as the heat transfer body 16 interposed between the sample table 11 and the insulator 18.
Since injum is a flexible metal, it can flexibly cope with sharp irregularities existing on the opposing surfaces of the sample table 11 and the insulator 18 under appropriate pressure. It can fill these irregularities and make good adhesion.
Thereby, the adhesion between the sample stage 11 and the insulator 18 is improved by several steps. In addition, since it is a metal, heat conduction is also very good.

Furthermore, unlike silicon grease, etc.
It does not leak from between the insulator 11 and the insulator 18 and contaminates the sample, and the cooling effect hardly decreases due to the change over time.

Here, FIG. 3 shows an experimental result in which a comparison was made between the case where the conventional silicon rubber and the silicon grease were used as the heat transfer body 16 and the case where the metal sheet (In sheet) according to the present embodiment was used. Show. Where RF-Power is the electrode layer 19
The output of the high-frequency oscillator connected to, plasma microwave 2 kw O ₂ plasma (gas pressure 1.2 mTorr) 5
The case where irradiation is performed for one minute is shown. In the case of (c) using a silicone rubber, the temperature of the sample 17 becomes 300 ° C. or higher,
In the case of (b) using silicon-based grease, the temperature of sample 17 was about 200 ° C., and in both cases, seizure was observed on the aluminum wiring on sample 17. However, in the case of (a) using the In sheet according to the present embodiment, the cooling effect by the sample stage 11 is improved, and the upper limit of the temperature on the sample 17 is also limited to 160 to 180 ° C., so that the aluminum wiring is seized. Was not found.

In this example, the In sheet was used as the metal sheet. However, if a metal sheet made of a metal having a melting point of about 150 ° C. or more and having flexibility, such as tin, lead, and an alloy containing them, is used, both surfaces of the metal sheet were used. The sample table 11 and the insulator 18 are satisfactorily adhered to each other, and the same effect as that of the present embodiment can be obtained.

In addition, the material is not limited to a metal sheet, but may be any sheet having good heat transfer and high flexibility. For example, a sheet of an organic composite material containing whiskers or fibers of a metal such as carbon or aluminum may be used.

Organic materials such as a polymer compound material having high flexibility are suitable for the base material of the organic composite material, and among them, at least 150
A material having a heat resistance of about ° C is particularly preferable.

Effect of the Invention As is clear from the above description, the sample holding device according to the present invention is a sample holding device including an insulator layer and a sample stage, and between the insulator layer and the sample stage, Since a metal sheet made of a flexible metal is interposed on both sides in close contact with each other, the flexible metal sheet penetrates into the insulator layer and the sharp unevenness generated on the surface of the sample table, This unevenness can be filled, and the contact area can be increased.

As a result, the heat conduction can be effectively used to obtain a sufficient cooling effect.
It is possible to prevent the etching resist from being deformed or deteriorated during the R etching or to suppress an adverse effect on the etched shape due to heat. Further, the aluminum wiring already formed is not lost, and therefore, it is easy to promote the high integration and miniaturization of the LSI.

Further, in a sample holding device composed of an insulator layer and a sample stage, a flexible organic composite containing thermally conductive fibers such as carbon and metal whiskers between the insulator layer and the sample stage. Even when a material sheet is interposed, the sheet has good adhesion to the sample stage and the insulator layer due to the flexibility of the organic composite material, and has high thermal conductivity secured by the heat conductive fiber. It becomes a heat body, and the same effect as in the case of the metal sheet can be obtained.

[Brief description of the drawings]

FIG. 1 shows a plasma provided with a sample holding device according to the present invention.
FIG. 2 is a schematic longitudinal sectional view of the CVD apparatus, FIG. 2 is an enlarged longitudinal sectional view of the sample holding apparatus of FIG. 1, and FIG. 3 is a case where a conventional silicon-based rubber or silicon-based grease is used as a heat transfer body and this embodiment. 7 is a graph showing test results when the In sheet according to Example 1 was used. 11 ... Sample stage, 15 ... Insulator layer, 16 ... Heat transfer material (metal sheet, organic composite sheet), 30 ... Sample holding device

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C23C 16/00-16/56 C23C 14/00-14/58 H01L 21 / 205,21 / 31,21 / 302 H01L 21/203

Claims (2)

(57) [Claims] In a sample holding apparatus provided with an insulator layer and a sample stage, a flexible metal sheet is interposed between the insulator layer and the sample stage by bringing both surfaces thereof into close contact with each other. A sample holding device, which is mounted. 2. A sample holding apparatus provided with an insulator layer and a sample stage, wherein both surfaces of the insulator layer and the sample stage are brought into close contact with each other to form a flexible material containing a thermally conductive fiber. A sample holding device, comprising a functional organic composite material sheet.