JPS6039831A - Treatment of semiconductor substrate - Google Patents

Abstract

PURPOSE:To enable to treat the surface of a wafer having uniform distribution on the surface by a method wherein susceptors holding the wafers, and partitions provided with gas circulating holes at the central parts and having the outer diameter the same with the inner diameter of a reaction chamber are arranged alternately. CONSTITUTION:Partitions 10 are provided with gas circulating holes 11 at the centers, and formed slidably in a reaction tube according to the frame parts 12 thereof. Susceptor holders 13 hold susceptors 16 according to pawl parts 15 provided with grooves 14, and formed slidably in the reaction tube. The partitions 10 are provided coming in contact with the inside wall of the raction tube 1, and moreover the diameter of the susceptor 16 is properly smaller as compared with the partition, and positioned along the central axis of the reaction tube 1. Reaction gas plasma extends in the reaction tube 1 along the susceptor 16 passing the gas circulating hole 11 positioned at the center of the partition 10, passes again in the gas circulating hole 11 of the adjoining partition 10, and this circulation is repeated to be discharged. Because radicals generated according to reaction gas plasma is circulated forcibly along the surfaces of wafers 5 in such a way, film thickness, distribution of film thickness of etching, etc. can be equalized.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a processing method for uniformly surface-treating a semiconductor substrate using a plasma apparatus.

(bl Technology background) Currently, thin film formation technology and photolithography are used to manufacture LSIs, but plasma equipment is often used in this process.In other words, silicon oxide (SiO
t) Processing such as formation of an insulating film such as silicon nitride (SiN4), removal of a resist film, or etching of a wafer can be performed by using this apparatus and changing the type of gas.

Although these treatments are carried out by arranging a plurality of wafers in the apparatus, it is necessary that the reaction be carried out uniformly on the surface of all the wafers 1.

(C1 Prior Art and Problems) There are two types of plasma devices: one in which the electrode for applying a high-frequency electric field is located inside the reaction chamber, and another in which the electrode for applying a high-frequency electric field is located outside the reaction chamber, and there are also capacitive type and fat conductive type depending on the electrode structure.

FIG. 1 shows a plasma device of a rust induction type employing an external electrode system, in which (4) is a front view and (B) is a side sectional view.

Silicon (St) wafer below, silicon nitride (Si4) on top
This function will be explained using an example in which a Ng) film is formed by direct nitriding. The reaction chamber 1 is made of transparent quartz, etc., and the front cap part 2 has a gas supply port 3, through which a constant flow of gas (in this case, ammonia NHs as the main component, CF"4, CHFs, etc.) is supplied through a gas, flow meter, etc. An auxiliary gas is added as a reaction promoter) into reaction chamber 1.
The exhaust port 4 is connected to an exhaust system and maintained at a constant degree of vacuum. On the other hand, a susceptor 16 carrying 5 tl of St wafers is arranged on a quartz holder 6 and inserted from the cap part 2, and a high frequency coil 7 is wound around the outside of the reaction tube 1, and a susceptor 16 of 13.56 MHz It is connected to a high frequency power source 8.

Now, when a high frequency electric field is applied in a state where a predetermined degree of vacuum has been reached, the gas starts discharging and generates gas plasma, the activated gas radicals react with Uni-No, and the remainder is exhausted through the exhaust port 4t.

That is, in this example, a thin film of Sis N4 is formed on the surface of the St wafer 5 mounted on the susceptor 16 by the reaction of 381 + 4NHs-+SiN4 +6Hz.

Here, the thickness of the 5LSN4 thin film is determined by the frequency of collisions of activated gas molecules with the substrate, so if the flow velocity distribution of the gas flow is not uniform on each surface of the wafer, the thickness of the 5LSN4 thin film is determined by the collision frequency of activated gas molecules with the substrate.
It is difficult to make sN4 thin films.

However, in order to increase work efficiency, the susceptor 16 on which the wafer 5 is set is placed at right angles to the gas flow in the center of the cylindrical reaction tube 1, as shown in FIG. ,N, is often difficult to fabricate, and becomes thinner toward the center of the wafer. Therefore, various efforts have been made to equalize the flow of gas and achieve uniform plasma discharge.

(d) Object of the Invention An object of the present invention is to provide a method for performing surface treatment on a wafer with uniform in-plane distribution using a plasma apparatus.

(e+ Structure of the Invention The purpose of the present invention is to adopt a method of alternately inserting and arranging a septa holding a wafer and a partition wall having a gas flow hole in the center and having an outer diameter equal to the inner diameter of the reaction chamber. What you achieve is colored by what you achieve.

Embodiment of the Invention Figure 2 shows a susceptor according to the present invention, and (6) is a side view, and Figure 3 shows a partition wall, and (B) is a side view.

In the present invention, a disk-shaped partition wall having a diameter y equal to the inner diameter of the reaction tube 1 is used to change the gas flow, thereby making the in-plane distribution uniform.

That is, the partition wall 10 has a gas flow port 11 in the center and a perpendicular frame part 12 around the periphery, and is made of quartz or the like and is slidable into the reaction tube. On the other hand, the susceptor holder 13 is similarly made of quartz or the like and holds a susceptor 16 made of carbon or carbon by means of claws 15 having grooves 14, and is formed so as to be slidable inside the reaction tube like the partition wall 10.

FIG. 4 shows an embodiment of the present invention in which the lid part 2 is opened and the reaction tube 1 is
A susceptor holder 13 with a partition wall 10 and a susceptor 16 set therein is alternately inserted, and as in the conventional case, gas is supplied from the gas supply port 3 and exhausted through the exhaust port 4 while applying a high frequency electric field to generate plasma. let

Here, the partition wall 10 is provided in contact with the inner wall of the reaction tube 1, and the susceptor 16 has a suitably smaller diameter than the partition wall, and is positioned along the central axis of the reaction tube 1, so that the reaction gas As shown by the arrow in the reaction tube 1, the plasma passes through the gas flow port 11 in the center of the partition wall 10, spreads along the susceptor 16, and then passes through the gas flow port 11 in the adjacent partition wall 10 again, repeating the process. Exhausted.

In this embodiment, the partition wall 10 and the susceptor holder 13
Although they are connected and provided, it is optional to provide them with an interval between them.

As described above, in the case of the present invention, the radicals generated by the reactive gas plasma Kj are forced to flow along the wafer surface, so that the reaction occurs uniformly, and the film thickness distribution such as film thickness and etching can be made uniform. It becomes possible.

The table shows Si, N, and insulating films formed to a thickness of 100 (A) by direct nitriding using plasma on a Si wafer with a diameter of 3 inches.
The average value of the film thickness distribution when formed as a Th target was set to 100, and the deviations on the + side and one side were calculated.

In addition, the throughput of NH is 200 (C94) and ^9
The degree is 40 (Pg).

As can be seen from the above results, a much more uniform in-plane distribution can be obtained compared to the conventional method. In the above embodiment, the quefer was placed on one side of the susceptor, but it may be placed on both sides, and by changing the gas system used, CVD-E or processing can be performed.

(g) Effects of the invention As the diameter of wafers used in the manufacture of semiconductor chips increases, the film thickness distribution becomes uneven when etching or film formation is performed using a plasma device, and the yield decreases. The film thickness distribution can be made uniform by implementing the present invention.

[Brief explanation of the drawing]

Figure 1 shows a conventional plasma device, (4) is a front view, and (B)
Side sectional view, Figure 2 is the susceptor, (4) is the front view, (B)
3 is a side view, FIG. 3 is a partition wall, and FIG. 3 is a front view, FIG. 4 is a side view, and FIG. 4 is a side sectional view of a plasma device embodying the present invention. In the figure, 1 is a reaction chamber, 3 is a gas supply port, 4 is an exhaust port, 5 is a wafer, 10 is a partition, 11 is a gas flow port, 13 is a susceptor holder, and 16 is a susceptor.

Claims (1)

[Claims] A plasma device that introduces a reaction gas into a reaction chamber in which a substrate to be processed is placed, maintains a reduced pressure state, applies a high-frequency electric field to generate a discharge, forms a plasma state, and causes radicals of the generated gas to react with the substrate to be processed. A plasma reaction is caused on the substrate by alternately inserting and arranging a susceptor holding the substrate to be processed and a partition having a gas flow port in the center and having an outer diameter equal to the inner diameter of the reaction chamber. A method for processing a semiconductor substrate, characterized by: