JP2002141335A - Silicon heater - Google Patents

Abstract

[PROBLEMS] To provide a heater capable of protecting a silicon wafer from contamination even if the silicon wafer is heated during plasma processing. The silicon heater 1 comprises:
In the heater arranged in the chamber 11 of the apparatus 10 for performing the plasma processing on the silicon wafer 20, the electrothermal resistor connected to the power supply is silicon. [Solution]

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon heater provided in an apparatus for performing a plasma processing on a silicon wafer for manufacturing a semiconductor.

[0002]

2. Description of the Related Art In a process of manufacturing a semiconductor, there is a process of subjecting a silicon wafer to plasma processing. For example, in plasma dry etching, a silicon wafer as an object to be processed is placed on a lower electrode, and a processing gas is ejected through the fine holes of the upper electrode having a large number of fine holes for rectifying the processing gas.
This is performed by applying a high-frequency voltage to the upper electrode and the lower electrode. Thereby, a plasma gas is generated and the silicon wafer is etched.

In order to improve the reliability and productivity of semiconductors, it is required to process wafers more uniformly. However, in the actual plasma processing step,
Due to the temperature rise associated with the processing, the temperature of the wafer may differ between the beginning and end of the process, or the temperature distribution may occur on the wafer surface, resulting in a difference in the etching rate. It had to be a good product.

Therefore, recently, in order to keep the wafer at a desired temperature from the beginning to the end of the plasma processing, a method of arranging a heater on the lower electrode side and heating the wafer to control the temperature to be constant has been adopted. I have. For example, JP-A-2000-54141 discloses a configuration in which a heating element is embedded in a substrate mounting table (lower electrode) of a vapor phase growth apparatus.

[0005] Such heating and temperature control can reduce the temperature difference due to the progress of the process and the temperature distribution on the wafer surface even if the temperature rises due to the plasma processing. Therefore, generation of contamination from a heater or the like is inevitable. Particularly, in a semiconductor in which an integrated circuit is miniaturized and highly integrated, even a very small contamination will result in a defective product. According to the description of JP-A-2000-54141, the substrate mounting table is made of ceramics,
The contact between the wafer and the substrate mounting table during the operation of holding and removing the wafer, and the exposure of the substrate mounting table itself to plasma may cause contamination.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems that occur during the plasma processing of a silicon wafer, and provides a heater that can protect the wafer from contamination even when heated during the plasma processing. Things.

[0007]

According to the present invention, there is provided a silicon heater to which the present invention is applied, wherein a heater disposed in a chamber of a plasma processing apparatus for a silicon wafer is an electric heating resistor connected to a power supply. Is silicon.

[0008] This silicon heater is used for heating in order to reduce the temperature difference and the temperature distribution on the wafer surface due to the progress of the process when the silicon wafer is subjected to plasma processing. Even if it becomes mist and adheres to a silicon wafer, it does not cause contamination.

[0009] The silicon heater may have a silicon soaking body closely attached to the electric heating resistor.

[0010] The temperature distribution on the wafer surface can be further reduced by having the soaking body. Also in this case, since the material of the heat equalizer is silicon, even if the silicon atomized at high temperature adheres to the silicon wafer, it does not cause contamination. In addition, by polishing the wafer mounting surface of the soaking body, the adhesion to the wafer is improved,
Heating can be performed efficiently.

[0011] Since the electric heating resistor and the soaking element are manufactured independently, it can be selected as a heater according to various shapes and conditions depending on the combination of the heating part and the soaking part. The running cost can be reduced because only the replacement is required.

The electric heating resistor has a continuum shape formed by patterning a silicon flat plate, and is appropriately formed by arranging a pair of electrodes for power supply connection at the farthest part of the continuation body. Can be implemented.

[0013] Such an electric heating resistor does not need to bury an electrode which is a heating element as in a conventional heater or to burn it on the surface of an insulator, so that the manufacturing process can be simplified and the shape can be changed or modified. High degree of freedom.

[0014] Preferably, the electric heating resistor and / or the soaking member are made of single crystal silicon. The electric heating resistor and / or the soaking element can be appropriately implemented by being covered with silicon carbide, silicon nitride, and diamond.

Since this coating layer has excellent plasma corrosion resistance, it does not become a source of particles even when exposed to plasma, and the surface can be coated many times even if the coating layer is deteriorated. In addition, the life as a heater can be maintained long. The CVD method or the like is effective for coating silicon carbide or the like, but other methods can also be used.

The minimum width of the continuum constituting the electric heating resistor is 1
mm or more is preferable, and when processing is made thinner than this, subtle deviations in dimensions have a large effect on the calorific value, causing unevenness in the temperature of the heater, and also having poor mechanical strength and may be damaged during handling. .

Since the specific resistance of the electric heating resistor is preferably 1 Ω · cm or less, and the material is silicon, it is easily available at a low cost because it is widely used as a wafer. Desirable for adjusting the resistance of Silicon, by its nature, has an electrical resistance value that depends on temperature. In particular, silicon having a specific resistance exceeding 1 Ω · cm greatly changes its electrical resistance depending on temperature, and it is difficult to use it stably as a heater. With silicon having a specific resistance of 1 Ω · cm or less, a stable heater having a small change in electric resistance value due to the temperature can be manufactured.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing one embodiment of the silicon heater of the present invention. FIG. 2 is a sectional view taken along line AA. The electric heating resistor 2 constituting the silicon heater 1 is obtained by cutting a silicon single crystal ingot and grinding the outer periphery to obtain a continuous body as shown in the figure by processing the disk by a diamond tool. Electrodes 5 and 6 are formed of aluminum foil at the farthest position of the continuum shape of the electric heating resistor 2 and connected to a heating power supply.

FIG. 3 is a sectional view showing another embodiment of the silicon heater of the present invention. The silicon heater 1 of this example has a coating 3 of silicon carbide on the surface of a continuum-shaped electric heating resistor 2 which is the silicon heater shown in FIGS.
It has been subjected to.

FIG. 4 is a partial sectional view of an example in which the silicon heater 1 is incorporated in a plasma dry etching apparatus 10. The silicon heater 1 also serving as a lower electrode is disposed on an insulating base plate 13 located at a lower portion in the chamber 11. The silicon heater 1 is obtained by superposing the continuum-shaped electric heating resistor 2 shown in FIG. 1 and FIG. A silicon wafer 20 to be processed is placed on the heat equalizer 4. Electrodes 5 and 6 of silicon heater 1 (see FIG. 1)
Are connected to a heating power supply via a temperature control circuit.

An upper electrode 17 is arranged in the upper part of the chamber 11 at a slight distance from the silicon wafer 20 and opposed to the silicon wafer 20. The lower electrode (silicon heater 1) and the upper electrode 17 are wired to a high voltage high frequency power supply. The upper electrode 17 is covered with a hood 18 and has a number of micro holes 19 for rectifying the processing gas. The hood 18 is connected to a processing gas supply source not shown.

This plasma dry etching apparatus 10
Supplies power from a heating power supply to the electrodes 5 and 6 of the silicon heater 1 and heats the silicon heater 1 to a constant temperature while supplying a processing gas to the lower electrode and upper electrode 17.
When a high-frequency voltage is applied during this period, a plasma gas is generated and the silicon wafer 20 is etched.

The silicon heater 1 can be widely used not only in the above-described plasma dry etching apparatus but also in an apparatus for processing a silicon wafer by plasma. For example, it can be used in a plasma CVD apparatus, a sputtering apparatus, and an ashing apparatus.

Hereinafter, examples in which the present invention is implemented will be described. Example 1 A silicon single crystal ingot having a specific resistance of 0.01 Ω · cm was cut, and its outer periphery was ground to φ200 × 6 mmt and φ2.
Two 00 × 15 mmt disks were obtained. φ200 × 6mm
The disk of t was polished to a thickness of 5 mmt by lapping and polishing to form a heat equalizing body 4. φ200 × 1
A 5 mmt disk was processed with a diamond tool of a machining center to form a continuum shape with an overall resistance of 2 Ω, thereby forming an electrothermal resistor 2. Electrodes 5 and 6 were formed of aluminum foil.

The silicon heater 1 in which the electric heating resistor 2 and the soaking element 4 are overlapped is installed in a plasma dry etching apparatus 10 as a lower electrode, and a silicon wafer 20 is mounted on the silicon heater 1 to perform plasma dry etching. gave. By controlling the temperature of the silicon heater, it was possible to maintain the temperature within the wafer surface at an accuracy of 200 ° C. ± 2 ° C.

In this state, 500 wafers were processed three times each (Examples 1-1 to 1-3). For comparison, 500 wafers were similarly processed three times using a conventional ceramic lower electrode having no heater function. Table 1 shows the number of non-defective products and the yield as a result of the processing.

[0027]

[Table 1]

Embodiment 2 An electric heating resistor and a soaking body were prepared in the same manner as in Embodiment 1, and silicon carbide was coated on each surface with silicon carbide by 200 μm by a CVD method. And the rest is in Example 1.
Similarly to above, plasma dry etching was applied to 500 wafers (Example 2-1). The one coated with 200 μm of silicon nitride instead of silicon carbide was used as silicon heater 1 (Example 2-2), and the one coated with 200 μm of diamond instead of silicon carbide was used as silicon heater 1 (Example 2). -3) Each of 500 wafers was subjected to plasma dry etching. For comparison, 500 wafers were similarly processed three times using a ceramic lower electrode having no heater function. The results of the processing are as shown in Table 2.

[0029]

[Table 2]

As described above, it was found that the yield was improved in each of the examples of the present invention using the silicon heater as compared with the comparative example. This is because the silicon heater keeps the temperature of the wafer uniform, enabling uniform processing in the plane. Furthermore, the heater itself is made of the same material as the wafer, which causes the generation of particles and contamination. It is because it is suppressed.

The effects of the surface coating layers of the electric heating resistor and the soaking element illustrated in Example 2 are not only the comparative examples, but are relatively superior to those of Example 1, and the effect of the diamond surface is particularly high. Excellent coating layer (Example 2-3), 10%
The above-mentioned improvement in yield was realized.

[0032]

As described above in detail, the silicon heater of the present invention is provided in an apparatus for plasma-treating a silicon wafer for manufacturing a semiconductor, thereby controlling the temperature of the silicon wafer during the plasma processing. The temperature difference due to the passage of time and the temperature distribution on the wafer surface can be reduced, but since the material is silicon, it does not cause contamination of the silicon wafer. Therefore, the yield of semiconductor manufacturing can be dramatically improved.

[Brief description of the drawings]

FIG. 1 is a plan view of an embodiment of a silicon heater to which the present invention is applied.

FIG. 2 is a sectional view of an embodiment of a silicon heater to which the present invention is applied.

FIG. 3 is a sectional view of another embodiment of the silicon heater to which the present invention is applied.

FIG. 4 is a partial cross-sectional view of an example in which the silicon heater of the embodiment to which the present invention is applied is incorporated in a plasma dry etching apparatus.

[Explanation of symbols]

1 is a silicon heater, 2 is an electric heating resistor, 3 is a coating, 4
Is a soaking body, 5.6 is an electrode, 10 is a plasma dry etching apparatus, 11 is a chamber, 13 is a base plate, 17 is an upper electrode, 18 is a hood, 19 is a fine hole, and 20 is a silicon wafer.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuyoshi Tamura 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Kagaku Kogyo Co., Ltd. Gunma Plant F-term (reference) 4K029 AA06 CA05 DA08 JA01 4K030 CA04 CA12 DA04 FA01 GA02 KA23 KA46 KA47 5F004 AA06 AA14 BA04 BB26 BB28 BC08 5F045 BB02 BB14 DP03 EF05 EH13 EK08

Claims (7)

[Claims] 1. A heater arranged in a chamber of an apparatus for plasma-processing a silicon wafer, wherein an electrothermal resistor connected to a power supply is silicon. 2. A silicon heater having a silicon soaking body closely attached to the electric heating resistor according to claim 1. 3. The method according to claim 1, wherein the electric heating resistor has a continuum shape formed by patterning a silicon flat plate, and a pair of electrodes for power supply connection is arranged at a farthest part of the continuation body. The silicon heater according to claim 1, wherein: 4. The silicon heater according to claim 1, wherein the electric heating element and / or the soaking element is made of single crystal silicon. 5. The silicon heater according to claim 1, wherein the electric heating element and / or the soaking element are coated with silicon carbide, silicon nitride, or diamond. 6. The specific resistance of the electric heating resistor is at most 1Ω.
2. The silicon heater according to claim 1, wherein the pressure is in cm. 3. 7. The silicon heater according to claim 4, wherein the minimum width of the continuum is 1 mm.