JPH04320031A - Wafer heating soaking plate - Google Patents

Abstract

PURPOSE:To turn a reaction gas plasmatic favorably by high frequency voltage by spraying a metal over the surface of a base made of a ceramic sinter to form a metal coating and by making the metal coating into a ground electrode corresponding to a shower electrode. CONSTITUTION:A soaking plate 22 is constituted of a ceramic sinter of any of silicon carbide, silicon nitride, zirconia, or alumina. A proper metal is sprayed over the surface of a base to form a metal coating 222, which serves as a ground electrode. In this case, the surface of the ceramic base 221 is made satinlike with proper roughness to improve adhesiveness with the metal, and the thickness (t) of the metal coating 222 is adjusted to about 0.1-0.5mm so as to prevent peeling. For grounding the metal coating as the ground electrode, the part of a step D provided at an edge of the base 221 is treated with a metal coating 222.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soaking plate for heating a wafer in a plasma CVD apparatus.

0002

2. Description of the Related Art In the manufacture of semiconductor ICs, there is a step of forming a thin film of silicon oxide on the surface of a wafer. Chemical vapor deposition (CVD) is used to form the thin film. There are three CVD methods: normal pressure method, reduced pressure method, and plasma method, but the plasma method is attracting attention as it has an advantage for the recent ultra-LSIs that require high-quality and high-precision thin films. There is. This method applies high-frequency voltage to a reactant gas injected into a vacuum to turn it into plasma.
It is superior in many respects, including the ability to obtain the energy necessary for the reaction, good film quality, and fast film formation speed.

FIG. 3 shows a vertical cross section of a plasma CVD apparatus. A housing 11 is fixed to a base board 10 to create an airtight structure,
The susceptor part 2 is fixed to the base board 10. Susceptor part 2
consists of a metal support frame 20, a heat equalizing plate 22, and a heater 21 for heating this. On the other hand, a gas injection section 4 is provided in the upper part of the casing 11. The injection part 4 is a metal nozzle 4
1 and a shower electrode 42, the susceptor portion 2 is used as a ground electrode, and a high frequency power source 5 is provided which applies a high frequency voltage to the shower electrode 42. In the reaction process, the gate 13 provided on the side surface of the casing 11 is opened, the wafer 3 to be processed is carried into the casing through the loading/unloading path 12 and placed on the soaking plate 22, and the gate is closed. to create a vacuum inside the housing. Next, heat is transferred to the wafer from the soaking plate heated by the heater to bring the wafer to a predetermined temperature, and the reaction gas sucked in from the inlet 43 is injected from the injection hole of the shower electrode. Here, when a high frequency voltage is applied to the shower electrode, the reaction gas is turned into plasma and diffused in the direction of the arrow, and a reaction product is deposited on the surface of the wafer to form a thin film. The gas after the reaction is exhausted to the outside through the exhaust port 14. In addition, case 1
The reaction state can be observed through a viewing window 15 provided on the side of 1.

0004

[Problem to be solved by the invention] The above plasma CVD
In the device, the conventional heat soaking plate 22 was made of an aluminum plate. However, the reaction requires heating the wafer to several hundred degrees Celsius, which causes the aluminum heating plate to curve. Further, since the wafer also has some degree of warpage, the wafer placed on the heat soaking plate comes into contact with a small number of points, resulting in temperature unevenness, which has the disadvantage of impairing the uniformity of the film quality. This invention was made to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a heat-uniforming plate with extremely small curvature due to heating.

[0005]

[Means for Solving the Problems] The present invention includes a heat soaking plate that is heated by a heater and on which a wafer to be processed is placed, and a shower electrode that is provided opposite to the heat soaking plate and that sprays a reaction gas. A soaking plate for wafer heating in a plasma CVD apparatus that is equipped with a high-frequency voltage between a shower electrode and a heat soaking plate to turn the injected reactive gas into plasma and form a thin film on the surface of the wafer to be processed. A ceramic sintered body is used as a base, and a metal coating is formed by spraying metal onto the surface of the base, and this is used as a ground electrode corresponding to a shower electrode. The ceramic sintered body constituting the base of the above heat soaking plate is formed by sintering silicon carbide, silicon nitride, zirconia, or alumina as a material.

[0006]

[Operation] Since the ceramic sintered body constituting the base of the heat equalizing plate described above is hardly deformed by heat, the problem of temperature unevenness caused in the wafer due to curvature is solved. However, ceramic sintered bodies are usually electrically insulating or semiconducting, and are unsuitable for forming a ground electrode. Therefore, the surface of the ceramic sintered body is coated with a metal to form a ground electrode, and this is used as a shower electrode. A high frequency voltage is applied in between. In the above, the ceramic sintered body of silicon carbide, silicon nitride, zirconia, or alumina that constitutes the base of the heat soaking plate is chemically stable against reactive gases, and is resistant to thermal shock and deformation such as curving. is extremely small, making it suitable for high-temperature structural materials.

[0007]

[Embodiment] FIG. 1 shows an embodiment of the present invention.
In No. 2, the base 221 is made of a ceramic sintered body of silicon carbide, silicon nitride, zirconia, or alumina. A suitable metal is sprayed onto the surface of the base to form a metal coating 222, which serves as a ground electrode. In this case, the surface of the ceramic base 221 has a satin finish with an appropriate roughness to improve adhesion to the metal, and the thickness t of the metal coating 222 is set to 0.1 to 0.5 m.
m or so to prevent peeling due to thermal expansion. Further, in order to ground the metal coating 222 as a ground electrode, the metal coating 222 is also applied to the step D provided at the end of the base 221.

FIG. 2 shows a susceptor section 2 of a plasma CVD apparatus to which the above-mentioned heat soaking plate 22 is applied. The susceptor part 2 is fixed to the base plate 10, a heat equalizing plate 22 is supported by a metal support frame 20, and a metal coating 222 is connected to the support frame 20 at a step D to serve as a ground electrode.

[0009]

[Effects of the Invention] As explained above, in the heating plate according to the present invention, silicon carbide constituting the base,
Ceramic sintered bodies of silicon nitride, zirconia, or alumina are all chemically stable against reactive gases, resistant to thermal shock, and have extremely low deformation such as curvature, making them suitable for high-temperature structural materials. This eliminates the problem of temperature unevenness that occurs on the wafer, and the metal coating applied to the surface of the base serves as a ground electrode, allowing the reaction gas to be turned into plasma by high-frequency voltage. This has a large effect in contributing to improving the quality of thin films.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

[Figure 2] Plasma CV using the soaking plate of this invention
It is a sectional view of the susceptor part of D device.

FIG. 3 is a vertical cross-sectional view of a plasma CVD apparatus.

[Explanation of symbols]

10... Base board, 11... Housing, 12... Carrying in/out path, 1
3...Gate, 14...Exhaust port, 15...Peep window, 2...Susceptor part, 20...Support frame, 21...Heater, 22...Soaking plate,
221...Base, 222...Metal coating, 3...Wafer to be processed, 4...Gas injection unit, 41...Nozzle, 42...
Shower electrode, 43...inlet, 5...high frequency power supply.

Claims (2)

[Claims] 1. A heat soaking plate heated by a heater and on which a wafer to be processed is placed, and a shower electrode provided opposite to the heat soak plate and spraying a reaction gas, the shower electrode and A plasma CVD apparatus that applies a high frequency voltage between the heating plate and the injected reaction gas to form a thin film on the surface of the wafer to be processed, the base being made of a ceramic sintered body; 1. A heat equalizing plate for wafer heating, characterized in that a metal coating is formed on the surface of the wafer by thermal spraying, and the metal coating is used as a ground electrode corresponding to the shower electrode. 2. The soaking plate for wafer heating according to claim 1, wherein the ceramic sintered body of the base of the heat soaking plate according to claim 1 is formed by sintering using silicon carbide, silicon nitride, zirconia, or alumina as a material. Board.