JPH0945595A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To promptly cool at the same time by removing moisture on a wafer by a method wherein, when a vacuum chamber is evacuated, nitrogen gas is flown within the vacuum chamber. SOLUTION: In a vacuum chamber having no load lock chambers, a wafer 1 is placed on a wafer stage 12 serving both as a liquid nitrogen container 13 and this is held by a wafer retainer 11. A temperature of the wafer 1 is measured by an optical fiber thermometer 9 from a rear face. There is provided a cooling nitrogen gas inlet 10 which flows nitrogen gas between the wafer stage 12 and the wafer 1. When the vacuum chamber is evacuated, the nitrogen gas is introduced under desired conditions from the cooling nitrogen gas inlet 10, while decompressed to cool the wafer 1 at -40 deg.C. Thus, a generation of frost in the wafer stage is prevented and also prompt cooling is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, in low-temperature process processing of semiconductor wafers, removes moisture in the vacuum chamber of the vacuum process processing apparatus and on the wafers to prevent frost formation and to provide rapid wafer processing. It is a method of cooling.

[0002]

2. Description of the Related Art FIG. 5 is an explanatory view of a conventional example. In the figure, 21 is a wafer, 22 is a vacuum chamber, 23 is a wafer stage with a cooling mechanism, 24 is a wafer transfer arm, and 25 is a load lock chamber.

FIG. 5 shows a typical example of a vacuum processing apparatus having a load lock chamber 25 for processing a semiconductor wafer 21 at a low temperature. Load lock chamber with wafer 21
At 25, evacuate. Then, the wafer 21 is placed on the wafer stage 23 with a cooling mechanism in the vacuum chamber 22 by the wafer transfer arm 24. After that, process processing such as etching of the wafer surface or film formation is performed.

[0004]

In the semiconductor manufacturing process, if the wafer is cooled without sufficiently removing the moisture adhering to the inside of the vacuum chamber and the wafer surface, the moisture becomes ice on the wafer surface or on the wafer stage with a cooling mechanism. , Water drops adhere to the wafer after the process.

The water droplets cause the generation of corrosion of the metal film or the like on the surface of the wafer, which is a problem in performing stable wafer processing. Therefore, to perform a low temperature process,
A relatively large vacuum processing device with a load lock chamber is required. Further, if the wafer stage and the wafer are not sufficiently in thermal contact, it takes time to cool the wafer.

[0006]

FIG. 1 is a diagram illustrating the principle of the present invention. In the figure, 1 is a wafer, 2 is a wafer stage with a cooling mechanism, 3 is a vacuum chamber, 4 is a reaction gas inlet, 5 is an exhaust port, 6 is an RF power source, 7 is an electrode, 8 is plasma, 9 is an optical fiber temperature. Reference numeral 10 is a cooling nitrogen gas inlet, 11 is a wafer holder, 12 is a wafer stage, and 13 is a liquid nitrogen container.

In order to carry out a low temperature process in a vacuum apparatus without a load lock chamber, it is necessary to remove water in the vacuum chamber 3 and on the wafer 1. In order to solve the above problems, first, as shown in the schematic cross-sectional view of the vacuum apparatus in FIG. 1A, when using a vacuum chamber 3 having a wafer stage 2 with a cooling mechanism for cooling a semiconductor wafer 1. When the vacuum chamber 3 is evacuated, a nitrogen gas is caused to flow into the vacuum chamber 3 to remove moisture on the wafer 1, and at the same time, perform rapid cooling.

[0008]

When the vacuum chamber is evacuated while introducing nitrogen gas, the water in the vacuum chamber is removed because the water adsorbed on the surface of the vacuum chamber and the wafer is replaced with nitrogen. .

The rapid cooling is also because nitrogen gas improves the thermal contact between the wafer stage and the wafer.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of the principle of the present invention and an explanatory view of a vacuum apparatus used in one embodiment, FIG. 2 is a schematic sectional view of a sample used in one embodiment of the present invention, and FIG. FIG. 4 is a diagram showing the relationship between the cooling time and the wafer temperature in one embodiment of the present invention.

In the figure, 1 is a wafer, 2 is a wafer stage with a cooling mechanism, 3 is a vacuum chamber, 4 is a reaction gas inlet, 5 is an exhaust port, 6 is an RF power source, 7 is an electrode, 8 is plasma, 9 is Optical fiber thermometer, 10 cooling nitrogen gas inlet, 11 wafer pressing, 12 wafer stage, 13 liquid nitrogen container, 14 Si substrate, 15 BPSG film, 16 Ti
A film, 17 is a TiN film, 18 is an AlCuTi alloy film, 19 is a sputtered Si film, and 20 is a resist film.

An embodiment of the present invention will be described with reference to FIGS. First, FIG. 1 is a schematic cross-sectional view showing the configuration of a vacuum device used in an embodiment of the present invention.

FIG. 1 (a) shows an overall configuration diagram. A vacuum chamber 3 without a load lock chamber has a wafer stage 2 with a cooling mechanism for mounting a wafer 1 to be processed therein, and is provided with a reaction gas inlet 4 and an exhaust port 5 for etching or film formation. is there. An RF power supply for plasma processing is externally connected to the wafer stage 2 with a cooling mechanism.

The wafer 1 is a wafer stage 2 with a cooling mechanism.
It is stored in. FIG. 1B shows a detailed view of the wafer stage with a cooling mechanism. The wafer 1 is placed on the wafer stage 12 which also serves as the liquid nitrogen container 13, and is held by the wafer retainer 11.

The temperature of the wafer 1 is measured by an optical fiber thermometer 9 from the back side. Between the wafer stage 12 and the wafer 1, there is a cooling nitrogen gas inlet 10 through which nitrogen gas flows. An embodiment of the present invention will be described.

In the plasma etching apparatus having the cooling nitrogen gas supply port 10 of the present invention, the nitrogen gas flow rate is 20 sccc.
The pressure was reduced while introducing nitrogen gas under the conditions of m and a pressure of 50 mTorr, and the wafer was cooled to −40 ° C. The cooling time at that time was 2 minutes.

The sample used in this example is obtained by patterning the layer structure shown in FIG. 2 with a line and space having a line width of 0.5 μm. It is known that this layer structure easily causes corrosion.

Aluminum (Al) under the above temperature conditions
The alloy film 18 was etched. The etching conditions at that time are shown in FIG. Then, the ashed sample was left in the atmosphere for one week, but no corrosion occurred. Further, at this time, frost was not formed on the wafer 1 and the wafer stage 2 with the cooling mechanism.

On the other hand, as a first comparative example, the same apparatus as in the example was cooled to −40 ° C. in the same sample as the example without introducing nitrogen gas. At that time, the time required for cooling was 3 minutes. At this time, frost adhered to the wafer 1 and part of the wafer stage 2 with the cooling mechanism.

This sample was etched under the same conditions as in the example. After the ashing treatment was further performed, the sample was left in the atmosphere for one week to cause corrosion. Also,
As a second comparative example, the same apparatus as in the example is used, the pressure is reduced without cooling, and then liquid nitrogen is introduced into the liquid nitrogen container 13 to cool the wafer.

The relationship between the cooling time and the temperature of the wafer at this time is shown in FIG. 4. Frost did not occur on the wafer 1 and the wafer stage 2 with the cooling mechanism, but the temperature drop was slow and the reached temperature was high. It was higher than the example.

[0022]

As described above, according to the present invention, the nitrogen gas is introduced into the vacuum chamber and exhausted, so that in a vacuum device without a load lock chamber, the wafer stage with a cooling mechanism in the vacuum chamber can be used. Frost is prevented and quick cooling is possible.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a sample used in one example of the present invention.

FIG. 3 is an etching condition of one embodiment of the present invention.

FIG. 4 shows the relationship between the cooling time and the wafer temperature according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 In the figure, 1 wafer 2 wafer stage with cooling mechanism 3 vacuum chamber 4 reaction gas introduction port 5 exhaust port 6 RF power source 7 electrode 8 plasma 9 optical fiber thermometer 10 cooling nitrogen gas introduction port 11 wafer holder 12 wafer stage 13 liquid nitrogen container 14 Si substrate 15 BPSG film 16 Ti film 17 TiN film 18 AlCuTi alloy film 19 Sputtered Si film 20 Resist film

Claims (1)

[Claims] 1. A method of manufacturing a semiconductor device, wherein when a vacuum chamber having a wafer stage with a cooling mechanism for cooling a semiconductor wafer is used, nitrogen gas is flown into the vacuum chamber when the vacuum chamber is evacuated.