JPS596509B2 - Processing method for semiconductor wafers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of processing a semiconductor substrate such as a silicon wafer using plasma-activated gas.

When manufacturing semiconductor devices, a resist layer, a metal layer such as aluminum, an insulating layer such as silicon nitride or silicon oxide, or a polycrystalline silicon layer is formed, and a portion of it is etched and removed to form a pattern. The process of doing so has become essential.

In recent years, plasma deposition methods have been widely used to form insulating layers such as silicon nitride films because they can be deposited at relatively low temperatures and have little effect on the characteristics of semiconductor devices. In addition, with the increasing integration and miniaturization of semiconductor devices, tetrafluoromethane (CF4) Ethane (C2F
6) Plasma etching methods using gases such as octafluoropropane (C3F8) and carbon tetrachloride (CCl4) are widely used. For example, a conventional apparatus for depositing a silicon nitride film on a silicon wafer and a deposition method using the same will be explained with reference to the cross-sectional view shown in FIG.

In this apparatus, a susceptor 2 on which a silicon wafer 1 is placed and a reaction gas supply device 4 are installed in a reaction chamber 3 to face the susceptor 2. A large number of gas blowing holes 5 are uniformly arranged in parallel at equal intervals on the opposing surface, and this surface is configured to be approximately parallel to the wafer 1 on the susceptor 2. Monosilane (SiH4) and ammonia (NH3) as reaction gases are routed from piping 6 to gas supply device 4 and supplied into reaction chamber 3 through hole 5. The internal pressure inside the reactor is controlled to 0.1 to 2 Torr by an exhaust pump (not shown). The gas supply device 4 and the susceptor 2 are each structured to serve as a high frequency electrode, and a high frequency is applied to them to generate plasma between them, thereby depositing a silicon nitride film on the wafer. The susceptor may be at room temperature, but the temperature is between 100 and 400℃.
It is often heated to a certain degree. A disadvantage of the conventional method is that the thickness of the resulting silicon nitride film is non-uniform and has large variations within the rod.

In the above example, the thickness of the silicon nitride film deposited on the wafer IA at the center is 1.
It is about 0-20% thinner. There are many possible causes for this, including the fact that the plasma effect is different between the center and the edges, and the temperature uniformity of the susceptor cannot be sufficiently controlled, but these have not yet been resolved to a satisfactory level. do not have.
The present invention makes it possible to correct the non-uniformity of the obtained film thickness and reduce the variation within the rod, and provides a method that is particularly effective in continuous production.

The apparatus used in the method of the present invention will be explained with reference to the sectional view shown in FIG.

Both the susceptor 2 and the gas supply device 4 are disk-shaped and have almost the same size, and are arranged in parallel to each other in the reaction chamber. The gas supply device is composed of two gas supply sections, ie, gas supply blocks 4A and 4B, and the portions 4B on both sides are connected to each other in an annular shape. Devices 7A and 7B for adjusting and setting the flow rate are connected to each of the pipes 6A and 6B for supplying gas to these blocks to control the flow rate of the reaction gas. A mass flow meter, a needle valve, or the like can be used as the flow rate adjustment/setting devices 7A, 7B. When forming a silicon nitride film using this deposition apparatus, first, a mixed gas consisting of monosilane (SiH4) and ammonia (NH3) is introduced into the pipes 6A and 6.
High-frequency power is applied in the same manner as in the conventional method while adjusting the flow rate adjusting and setting devices 7A and 7B so that the amount supplied to each block 4B at the peripheral edge increases. Under such condition settings, the amount of reactive gas supplied to the silicon wafer 1B will be greater than the amount of reactive gas supplied to the silicon wafer 1A, and the tendency for the film thickness of the silicon wafer 1B located at the periphery to become thinner will be corrected. be done.

Therefore, the thickness of the silicon nitride obtained was uniform and had good reproducibility. In the above explanation, when the film deposited on the wafer 1B located at the peripheral edge tends to become thinner, the gas supply device 4B corresponding to this position is
We have exemplified the case where this tendency is corrected by increasing the amount of reactant gas supplied from the film to make the film thickness uniform.
When there is a tendency for the film thickness to become thinner in the center, contrary to the above-mentioned tendency, the adjustment by the mixed gas flow rate setting device is reversed to the above, and a large amount of reactive gas is supplied to the silicon wafer 1A located in the center. This tendency can be eliminated by

Note that the flow rate can be determined experimentally. Furthermore, in the case of continuous production, variations can be further reduced by setting the gas flow rate in consideration of the results of the immediately previous rod and depositing the next rod.

According to the method of the present invention, the supply amount of the reaction gas can be adjusted and set with some degree of freedom, so variations that occur due to fluctuations in various conditions can be reduced by correcting the gas flow rate each time during manufacturing. There is an advantage that it can be suppressed.

In the above explanation, the gas supply device was made into two blocks, but
You can control more finely by setting 3 or more, and you can also set 1
It is also possible to partially use a configuration in which one gas flow rate adjustment setting device is connected to a plurality of procs. Further, although the deposition of a silicon nitride film is taken as an example, the present invention can also be applied to the deposition of other films such as silicon oxide. Further, even in response to variations in etching using plasma, an apparatus according to the spirit of the present invention can be used as long as the amount of etching changes depending on the amount of reactant gas supplied. As described above, according to the method of the present invention, it is possible to improve the non-uniformity of the film thickness of various material layers deposited by plasma or the non-uniformity of the etching amount of various films subjected to ptezuma etching. I can do it.

In particular, when performing continuous processing, it is possible to feed back the results of the immediately preceding processing rod, and it has excellent industrial advantages such as being able to respond to changes in various conditions and further reducing dispersion. It is.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a plasma processing apparatus used in a conventional method, and FIG. 2 is a sectional view of a schematic structure of a plasma processing apparatus used in the method of the present invention. 1...Wafer, 2...Susceptor, 4
A, 4B・・・Protect part of gas supply device, 6A
, 6B...Piping, 7A, 7B...Flow rate adjustment setting device.

Claims (1)

[Claims] 1. A first reactive gas jetting block facing the peripheral part of a susceptor in which a large number of semiconductor wafers can be two-dimensionally arranged; A plurality of semiconductor wafers are two-dimensionally arranged on the susceptor of a plasma processing apparatus having a reaction gas supply device formed by a second reaction gas ejection block facing the first and second reaction gas ejection blocks. Reactant gases with different flow rates are sent to the two reactive gas jetting blocks, and different amounts of reactive gases are supplied from the reactive gas jetting holes of each reactive gas jetting block onto the two-dimensionally arranged semiconductor wafers, thereby simultaneously processing a large number of semiconductor wafers. A semiconductor wafer processing method characterized by plasma processing.