JPH0656845B2 - Method for manufacturing semiconductor device - Google Patents

Description

Description: TECHNICAL FIELD The present invention is intended to prevent physical damage to a wafer inserted in a reactor in a wafer process of removing a photosensitive resin using oxygen gas plasma. The present invention relates to a method of manufacturing the semiconductor device.

[Prior art]

Owing to the recent progress in the performance improvement of semiconductor elements, especially integrated circuits, oxygen gas plasma is used in the wafer process for removing the photosensitive resin due to the need for process technology such as dry etching or ion implantation. The method is established as an essential method. In a wafer process for removing this type of photosensitive resin, a batch method is used in which a plurality of wafers are simultaneously processed for the purpose of its processing capacity or simple removal action. FIG. 1 is a cross-sectional view showing a conventional method for manufacturing a semiconductor element, and particularly shows a wafer process for removing a photosensitive resin. In the figure,
(1) is a quartz reaction tube, (2) is a quartz glass wafer platform that supports a plurality of wafers (3), (4) is an oxygen gas inlet, and (5) is an oxygen gas outlet. Is.

The arrows shown on the wafer (3) indicate the direction of the wafer surface, and the wafers (3) are all arranged in a fixed direction.

Next, in the wafer process for removing the photosensitive resin having the above configuration, for example, the frequency is 13.56 MHz, the discharge output is 1 K.
It is operated under the conditions of W and oxygen gas pressure of 2 Torr.

However, in the conventional method of manufacturing a semiconductor device, the impact of excited molecules or electrons becomes non-uniform between wafers due to the non-uniformity of the localized plasma discharge. Due to the physical damage to the wafers caused by this impact, the electrical characteristics of the semiconductor elements change, and the electrical characteristics between the wafers become non-uniform. At times, in a semiconductor device using a MOS transistor, the energy level of the silicon oxide film is changed due to the influence on the silicon oxide film on the silicon wafer substrate, and the threshold voltage (V _TH ) which is a typical device characteristic is changed. Change. That is, FIG. 2 shows a frequency of 13.56 MH, for example.
MO under the conditions of Z, discharge output 1KW and oxygen gas pressure 2 Torr
During the manufacturing process of the S-type transistor, the threshold voltage (V _TH ) when exposed for 60 minutes during plasma discharge after the silicon oxide film for the gate is formed depends on the position of the wafer (3) on the wafer mount (2). , Is a plot. In FIG. 2, Nos. 1 to 25 on the horizontal axis are wafers on the wafer mount (2).
The order of (3) is shown, and the vertical axis shows the threshold voltage (V _TH ).
(A) shows the case of N channel MOS transistor, (B)
Shows the case of a P channel MOS transistor. According to this FIG. 2, No. 1 located at the end on the wafer mount (2)
It can be seen that the wafer characteristic is abnormal, and that it is one side edge. As described above, conventionally, there is a drawback that the threshold voltage (V _TH ) of the wafer located at the end of the wafer pedestal (2) changes.

[Outline of Invention]

Therefore, the object of the present invention is to prevent a plurality of wafers inserted in a reactor from being physically damaged, and to make sure that all wafers have a constant threshold voltage (V _TH The present invention provides a method for manufacturing a semiconductor device that can be formed so as to have

In order to achieve such an object, according to the present invention, in the process of removing a photosensitive resin by oxygen gas plasma during a process of manufacturing a semiconductor device, a plurality of wafers are evenly parallel in a reactor and the wafer surface thereof is Are arranged so as to face in one direction, and only one wafer at the outermost end is arranged in a direction opposite to the one direction so that the wafer surface faces the surface of an adjacent semiconductor wafer. Furthermore, a shielding plate is arranged so as to face the wafer surface at the outermost end and at an interval substantially the same as the semiconductor wafer interval. This will be described in detail below with reference to examples.

Example of Invention

FIG. 3 is a schematic cross-sectional view showing an embodiment of a method for manufacturing a semiconductor device according to the present invention. Particularly, during the manufacturing process of a MOS type transistor, a plurality of wafers (3) are arranged on a wafer mount (2). Shows a wafer process for removing the photosensitive resin. In this embodiment, a plurality of wafers (3) are evenly arranged on the wafer pedestal (2) so that their wafer surfaces face in one direction, and only one wafer at the end is Arrange so that the wafer surface faces inward. As a result, the surfaces of the wafers at both ends face inward.

When removing the photosensitive resin, for example, frequency 1
Under the conditions of 3.56 MHZ, discharge output of 1 KW, and oxygen gas pressure of 2 Torr, the threshold voltage (V _TH ) when exposed to plasma discharge for 60 minutes after the formation of the silicon oxide film for the gate during the manufacturing process of the MOS transistor. FIG. 4 shows a plot of the wafer depending on the position of the wafer (3) on the wafer mount (2).
In FIG. 4, No. 1 to No. 25 on the horizontal axis indicate the order of the wafer (3) on the wafer mount (2), and the vertical axis indicates the threshold voltage (V
Show _TH), (A) shows the case of N channel MOS transistors, shows the case of (B) is P-channel MOS transistor. According to this FIG. 4, the photosensitive resin of the plurality of wafers (3) arranged on the wafer mount (2) can be removed, and the threshold voltage (V _TH ) can be made substantially uniform. .

FIG. 5 is a schematic sectional view showing another embodiment. In the figure, (6a) and (6b) are shielding plates installed at both ends of the wafer mount (2), having a thickness of, for example, about 1 mm and having substantially the same shape as the shape of the wafer (3).

The shield plates (6a) and (6b) are shown installed at substantially the same intervals as the wafer (3).

By arranging the shielding plates (6a) and (6b) in this manner, for example, under the conditions of frequency 13.56MHZ, discharge output 1KW, oxygen gas pressure 2 Torr, silicon for gate during the manufacturing process of the MOS type transistor. When exposed to plasma discharge for 60 minutes after the oxide film was formed, the same characteristics as in FIG. 4 were obtained. Thus, the photosensitive resin of the plurality of wafers (3) arranged on the wafer mount (2) can be removed, and the threshold voltage (V _TH ) can be made almost uniform. .

In the above-described embodiment, the case where two shield plates are provided is shown. However, when the wafer surfaces are arranged so as to always face in a certain direction, for example, when the wafer surfaces are arranged in the illustrated direction, the shield plates (6b ) Is not always necessary, and similarly, the shield plate (6a) is not necessarily required when the elements are arranged in the direction opposite to the illustrated direction. In addition, the shielding plate (6
A) and (6b) may be provided detachably or fixedly.

〔The invention's effect〕

As described in detail above, according to the semiconductor element manufacturing process of the present invention, the characteristics of a plurality of wafers can be made uniform in the wafer process of removing the photosensitive resin using oxygen gas plasma. It is especially effective for processes susceptible to plasma damage, such as thinning of the gate oxide film for high integration and high performance devices.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a conventional method for manufacturing a semiconductor device, FIG. 2 is a view showing a threshold voltage (V _TH ) of each wafer at each wafer position in FIG. 1, and FIG. 3 is a semiconductor according to the present invention. FIG. 4 is a schematic sectional view showing an embodiment of a method for manufacturing the device,
FIG. 5 is a diagram showing the threshold voltage (V _TH ) of each wafer at each wafer position in the figure, and FIG. 5 is a schematic sectional view showing another embodiment. (1) …… Reaction tube, (2) …… Wafer mount, (3) …… Wafer,
(4) …… Inlet port, (5) …… Exhaust port, (6a), (6b) …… Shield plate.

Claims (1)

[Claims] 1. A method of removing a photosensitive resin formed on a surface of a semiconductor wafer by oxygen gas plasma during a manufacturing process of a semiconductor device, wherein a plurality of the semiconductor wafers are evenly parallel in a reactor, and The semiconductor wafer surface is arranged so as to face in one direction, and only one semiconductor wafer at the end is arranged in a direction opposite to the one direction so that the semiconductor wafer surface faces the surface of an adjacent semiconductor wafer. A method of manufacturing a semiconductor element, wherein the semiconductor element is disposed and the photosensitive resin is removed by oxygen gas plasma.