JPH03151629A - Manufacturing equipment for semiconductor thin film and manufacture of semiconductor multilayer thin film - Google Patents

Abstract

PURPOSE:To prevent dust from attaching on a substrate arranged between electrodes and stably supply gas, by surrounding the periphery of plasma forming electrodes for decomposing gas installed in a reaction chamber, by using a metal wall equipped with a lot of holes. CONSTITUTION:The periphery of electrodes 3, 4 in a reaction chamber are covered with a metal wall 10 equipped with a lot of holes 5. The external part of the metal wall is constituted so as to be closed to the atmosphere. Reactant gas 15 is introduced into the reaction chamber from a lot of the holes 5 arranged on the metal wall 10 on the periphery of the electrodes 3, 4, so that the reactant gas 15 uniformly flows in the reaction chamber from the peripheral part, thereby obtaining a stable gas flow between the plasma electrodes 3, 4. Further the plasma electrodes 3, 4 are equipped with a lot of holes 5 to constitute an exhaust system, so that the gas reaching the part between the electrodes 3, 4 flows from the upper electrode 3 fixing substrates 1 toward the lower electrode 4 provided with the exhaust system. Hence, when dust is generated, it is hard to reach the substrate surface because of gas flow, so that the dust can be prevented from attaching on the substrate during mask formation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to plasma CVD for manufacturing semiconductor thin films.
D (Chemical aper Daposjt
ion (chemical vapor deposition) apparatus.

Conventional technology The gas introduction system of a conventional parallel plate plasma CVD apparatus is as follows:
There are those that introduce the reaction gas from the side wall of the reaction chamber and those that introduce the gas through a number of holes provided in the plasma electrode. In addition, a system for exhausting these gases is provided on the side wall or lower part of the reaction chamber. For example, FIGS. 2A and 2B show schematic diagrams of a conventional gas introduction system and exhaust system. Figure 2 (A)
In this case, gas is introduced from the side wall of the reaction chamber and exhausted from the side wall. In such a structure, the gas flow becomes laminar from the introduction system to the exhaust system. This makes it difficult to uniformly form a film on the substrate, and to prevent this, the substrate support is provided with a rotation mechanism. Figure 2 (
In B), a gas introduction system is provided in a plasma electrode having a large number of holes. By adopting such a structure, the gas becomes uniform around the electrode, and it is possible to uniformly form a film on the substrate.

However, with this structure, there is a possibility that the film deposited on the plasma electrode may be rolled up by the gas flow, causing dust during film formation. In addition, in a gas introduction system with such a structure, when introducing gas into a reaction chamber in a high vacuum state, there is a possibility that rapidly cooled gas may be sprayed onto a heated substrate in the direction of the substrate. may cause contamination of the parts. In order to prevent this, some methods employ a method of heating the reaction gas to a certain temperature before introducing the gas into the reaction chamber, and then introducing the heated gas into the reaction chamber.

111 Problems to be Solved by the Invention The conventional parallel plate plasma CVD apparatus described above has the following problems.

First, since gas flows from the gas introduction system to the exhaust system, it is difficult to make the reaction gas uniform between the upper and lower electrodes. In addition, introducing gas from the plasma electrode to stabilize the gas between the electrodes may cause dust to be rolled up onto the substrate, or gas may be introduced into the heated substrate at the beginning of the reaction chamber in a high vacuum state. Spraying may affect film growth.

Means for Solving the Problems In the present invention, in order to solve the above problems, the periphery of the electrode in the reaction chamber is covered with a metal wall having a large number of holes, and the outside of the metal wall is closed from the atmosphere. .

A reaction gas is introduced into the chamber thus constructed as a gas storage chamber, and the gas flows through holes provided in the metal wall to the electrodes. Also, at least one first exhaust system is installed in this gas reservoir chamber.
We have set up more than one. Moreover, inside the metal wall is a plasma electrode provided with a large number of holes, and a second exhaust system (B) is connected thereto for exhausting the reaction gas. Further, in addition to the second exhaust system, a third exhaust system is provided at the bottom of the reaction chamber.

Function: In the plasma CVD apparatus manufactured according to the present invention, the reaction gas is introduced into the reaction chamber through a large number of holes provided in the metal wall around the electrode. A stable gas flow can be obtained between the two. Furthermore, since the plasma electrode has a large number of holes and is used as an exhaust system, the gas that reaches between the electrodes flows from the upper electrode to which the substrate is fixed to the lower electrode, which has an exhaust system. However, the gas flow makes it difficult for the gas to reach the substrate, and it is possible to prevent dust from adhering to the substrate during film formation.

In addition, by making the conductance of the third exhaust system installed at the bottom of the reaction chamber larger than the conductance of the second exhaust system, the entire gas flow is directed from the metal wall to the bottom of the reaction chamber, and dust is raised between the electrodes. is prevented. The first exhaust system provided in the gas storage chamber is used to exhaust the inside of the reaction chamber, and gas can be switched at high speed when forming a multilayer thin film in the same reaction chamber.

Embodiment FIG. 2 shows a schematic diagram of a parallel plate type plasma CVD apparatus according to the present invention. FIG. 2(A) is a sectional view seen from the front, and FIG. 2(B) is a sectional view seen from above. A substrate 1 is fixed to an upper electrode 3 having a heater 2 for heating the substrate. In addition, holes 5 are arranged concentrically in the lower electrode 4.
A buffer space 6 with the second exhaust system is provided below the electrode so as to cover the entirety of these holes, and a pipe 7 of the exhaust system is connected to the center of this space. At the bottom of the reaction chamber, piping 9 of a third exhaust system is provided at four locations symmetrically around the lower electrode 4. Here, the conductance of the pipe 9 is made sufficiently larger than that of the pipe 7. Next, the periphery of the electrodes is covered with a metal wall 10, and holes 11 for introducing gas are regularly provided therein with a width wider than between the electrodes. A gas reservoir chamber 12 closed to the atmosphere is provided outside the metal wall 10, and gas pipes 13A, 13B and a first exhaust system piping 14 are connected to this gas reservoir chamber.

Next, a method for forming a semiconductor thin film using the plasma CVD apparatus configured as described above will be described. First, the substrate 1 is attached to the upper electrode 3, and the exhaust system piping 14,
9. Open the valves 7 in this order to exhaust air. When a high vacuum state is reached, the valves of the exhaust system piping 7 and 9 are closed in this order.

At this time, the reaction chamber is evacuated only through the exhaust system piping 14. After introducing H2 gas from 13B in this state, the exhaust system piping 9 and 7 are opened in this order, and when the reaction chamber reaches a predetermined pressure, the exhaust system piping 14 is closed and the substrate 1 is heated to a predetermined temperature by the heater 2. do. When the temperature of the substrate 1 is stabilized at a predetermined temperature, the gas pipe 13B is closed to exhaust the gas. When exhausting the gas in the reaction chamber, first open the exhaust system piping 14 while there is gas in the reaction chamber, close the exhaust system piping 7 and 9 in this order, and perform initial exhaust through the exhaust system piping 14. .

When the degree of vacuum reaches a certain value, the exhaust system piping 9.7 is opened again in this order to evacuate to a high vacuum state.

When a high vacuum state is obtained, the exhaust system piping 7.9 is closed in this order in order to introduce the reaction gas into the reaction chamber. next,
For example, in order to form a first film, a reaction gas in which SiH gas and H2 gas are mixed in advance at a certain mixing ratio is flowed into the gas reservoir chamber 12 through the gas pipe 13A of the apparatus. At the initial stage when the reaction gas is introduced into the gas reservoir chamber, the reaction gas is exhausted only through the exhaust system piping 14, and as described above, by opening the exhaust system piping 9 and 7, the reaction gas is discharged into the reaction chamber and between the electrodes. Gas will be introduced. Thereafter, when the pressure in the reaction chamber reaches a predetermined pressure using the pressure controller, the valve of the exhaust system piping 14 is closed and discharge is started between the upper electrode 3 and the lower electrode 4 to form a film. At this time, since the conductance of the exhaust system piping 9 is larger than the conductance of the exhaust system piping 7, the reaction gas as a whole flows from the hole in the metal wall to the exhaust system piping 9.
flowing towards. Further, the reactive gas that has diffused between the electrodes is decomposed by the plasma and adheres to the substrate. In this way, a semiconductor thin film is formed. Here, when the film formation of the first film is completed, the exhaust system piping 7.9 is closed in this order and the exhaust system piping 14 is opened.

Thereafter, the reaction gas is exhausted from the reaction chamber using the same procedure as the H2 gas exhaust method described above.

Next, a second film is formed. For example, S + H4H2
, a reaction gas containing a mixture of N2 and NH3 gas is supplied to the gas pipe 13.
Gas introduction, film formation, and exhaust are performed in the same manner as when forming the first film using B. In this way the first
By alternately forming the first film and the second film, a high-quality semiconductor multilayer film can be efficiently formed in one reaction chamber.

Effects of the Invention As mentioned above, by always using the first, third, and second exhaust systems in the order of gas introduction and exhaust, it is possible to prevent dust from adhering to the substrate attached between the electrodes. It is possible to prevent this and provide a stable gas supply. In addition, by making the semiconductor II film manufacturing apparatus into such a structure,
Since the gas in the reaction chamber can be exhausted at high speed and there is almost no effect on the substrate due to gas switching, it is possible to form a good multilayer thin film in a single reaction chamber.

[Brief explanation of the drawing]

FIG. 1 shows the structure of a plasma CVD apparatus according to the present invention. 1... Board, 2... Heater, 3...
...Top electrode, 4...Bottom electrode, 5...
... Hole, 6 ... Exhaust buffer chamber, 7 ... Exhaust system piping, 8 ... Insulating material, 9 ...
Exhaust system piping, 10...Metal wall, 11...
・Gas introduction hole, 12...Gas reservoir chamber, 13A
...Gas introduction piping, 13B...Gas introduction piping, 14...Exhaust system piping, 15...
・Reactive gas. 1

Claims (8)

[Claims] (1) In a semiconductor thin film manufacturing apparatus that forms a semiconductor thin film by decomposing a reactive gas, a
A semiconductor thin film manufacturing apparatus characterized in that a plasma forming electrode for decomposing gas is surrounded by a metal wall having a large number of holes. (2) On the outside of the metal wall surrounding the plasma forming electrode, there is a gas reservoir chamber for introducing reaction gas, which is closed from the atmosphere and covered by the metal wall, so that the reaction gas introduced from outside the device is 2. The semiconductor thin film manufacturing apparatus according to claim 1, wherein the gas flows into the reaction chamber through the gas storage chamber. (3) The semiconductor thin film manufacturing apparatus according to claim (1), further comprising a first exhaust system for exhausting the reaction gas into the gas reservoir chamber. (4) In order to decompose the reaction gas, plasma forming electrodes consisting of parallel plates are used. Among these parallel plate electrodes, the first electrode has a structure for fixing and heating the substrate, and the second electrode has a structure for fixing and heating the substrate. A semiconductor thin film manufacturing apparatus comprising a metal plate having a large number of holes, at least one of which is connected to a second exhaust system. (5) The first electrode having a structure for fixing the substrate is provided in the upper part of the reaction chamber, and the second electrode having a second exhaust system is provided in the lower part of the reaction chamber. Semiconductor thin film manufacturing equipment. (6) In the reaction chamber, in addition to the second exhaust system provided at the second electrode, at least one third exhaust system is provided at the bottom of the reaction chamber, and the conductance of this third exhaust system is 5. The semiconductor thin film manufacturing apparatus according to claim 4, wherein the conductance is made larger than the conductance of the second exhaust system. (7) When forming a semiconductor multilayer thin film, the semiconductor thin film manufacturing apparatus described above is used, which is provided with a gas introduction system surrounding the plasma forming electrode and an exhaust system in the gas reservoir, the lower part of the reaction chamber, and the lower electrode. A method for manufacturing a semiconductor multilayer thin film. (8) When introducing gas using the semiconductor manufacturing apparatus, initial exhaust is performed with the first exhaust system with the second and third exhaust systems closed, and then the third exhaust system, The second exhaust system is sequentially opened to introduce gas into the reaction chamber, and
When evacuating a reaction chamber from a state where there is gas to a high vacuum state, the second exhaust system and the third exhaust system that are in the exhaust state are closed in order, and the gas is exhausted from the first exhaust system first. 8. The method of manufacturing a semiconductor multilayer thin film according to claim 7, wherein the third exhaust system and the second exhaust system are sequentially opened again.