JPH04249341A - Plasma processing machine - Google Patents

Abstract

PURPOSE:To improve the efficiency of plasma processing in the vicinity of the orientation flat of a wafer by providing a continued wafer-pressing margin of a wafer presser along the periphery of the wafer. CONSTITUTION:A wafer 1 is disposed in a vacuum chamber, and the wafer 1 is processed by generating a plasma with the edge thereof being pressed by means of a wafer presser 10. In a plasma processing machine having such an arrangement, a wafer-pressing margin of the wafer presser 10 is continuously provided along the periphery of the wafer 1. The wafer presser 10 is to securely situate the wafer 1 in position by pressing the edge of the same. For instance, all of the periphery of the wafer 1, disposed upon the surface of a bottom electrode 2, is pressed by the wafer presser 10 matched, in shape, with the wafer 1, thereby eliminating a gap between the orientation flat 1a of the wafer 1 and the wafer presser 10. This prevents a processing gas from being expelled by a cooling gas, whereby the uniformity in processing is ensured over the surface of the wafer.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus for plasma processing a wafer in a semiconductor process.

0002

2. Description of the Related Art FIG. 3 is a cross-sectional view a showing a parallel plate type upper and lower electrode section provided in a conventional vacuum chamber, and a plan view thereof taken along line B-B. 1 is placed on a lower electrode for applying high frequency waves; 3 is a cooling gas outlet provided on the lower electrode 2 to flow cooling gas onto the back surface of the wafer 1; 4 is a wafer holder for fixing the wafer 1 so that it does not shift. , 5 is an upper electrode, and 6 is a processing gas ejection hole provided in the upper electrode 5.

Next, the operation will be explained. The wafer 1 is placed on the lower electrode 2 and the wafer holder 4 is placed over the wafer 1 to fix the wafer 1, and then cooling gas is flowed into the back surface of the wafer 1 from the cooling gas outlet 3. On the other hand, a processing gas is introduced from a processing gas outlet 6 provided on the surface of the upper electrode 5, and after the vacuum pressure reaches a desired pressure, a high frequency is applied to the lower electrode 2 to generate plasma between the upper and lower electrodes. The wafer 1 is then processed.

0004

[Problems to be Solved by the Invention] The conventional plasma processing apparatus is constructed as described above, and since the orientation flat 1a of the wafer 1 is located inside the inner diameter of the wafer holder 4, the wafer 1 and As shown in FIG. 4, an opening 7 is formed between the opening 7 and the wafer holder 4, through which the cooling gas 8 introduced to the back surface of the wafer 1 flows out between the upper and lower electrodes as shown at 8a. When such a phenomenon occurs, the processing gas 9 ejected from the processing gas ejection hole 6 of the upper electrode 5 is removed by the cooling gas 8a flowing out from the opening 7 as shown in 9a, and the wafer orientation flat near the opening is removed. There was a problem in that the plasma processing efficiency of some parts decreased.

[0005] This invention was made to solve the above-mentioned problems by preventing the phenomenon in which wafer cooling gas flows out between the upper and lower electrodes from the gap between the wafer orientation flat and the wafer holder. The purpose is to improve plasma processing efficiency near the wafer orientation flat.

[0006]

[Means for Solving the Problems] In the plasma processing apparatus according to the present invention, the shape of the holding portion of the wafer holder that presses the periphery of the edge of the wafer to fix the wafer is the same as the shape of the wafer.

[0007]

[Operation] The wafer presser of this invention presses the entire circumference of the wafer according to the shape of the wafer, including the orientation flat of the wafer, so that cooling gas flows out between the upper and lower electrodes from around the orientation flat of the wafer. This eliminates the phenomenon of processing gas being eliminated due to cooling gas flowing out near the orientation flat of the wafer, and improves the drop in plasma processing efficiency near the orientation flat of the wafer.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, which correspond to FIGS. 3 and 4 above, 1
0 is a wafer holder that fixes the wafer 1 placed on the surface of the lower electrode 2 by pressing the periphery of the wafer edge so that the wafer 1 does not shift. The entire periphery of the wafer 1 is held down without leaving a gap between the orientation flat 1a of the wafer 1 and the wafer holder 10 as in the conventional example.

As described above, after the wafer 1 placed on the surface of the lower electrode 2 is held and fixed by the wafer holder 10, the cooling gas 8 is introduced from the cooling gas outlet 3 to the back surface of the wafer 1. The cooling gas flows uniformly onto the back surface of the wafer 1 and is exhausted through the gap between the lower electrode 2 and the wafer holder 10 without spewing out between the upper and lower electrodes.

0010

As described above, according to the present invention, the cooling gas ejected from the cooling gas outlet to the back surface of the wafer flows uniformly onto the back surface of the wafer, and then passes between the wafer holder and the lower electrode. This improves the phenomenon in which the cooling gas eliminates the processing gas introduced between the upper and lower electrodes, allows the wafer to be efficiently processed with plasma, and improves the uniformity of processing within the wafer surface. There is an effect that can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a plasma processing apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view taken along line AA in FIG. 1;

FIG. 3 is a sectional view showing a conventional plasma processing apparatus.

FIG. 4 is a plan view taken along line BB in FIG. 3;

[Explanation of symbols]

1 Wafer 2 Lower electrode 3 Cooling gas outlet 5 Upper electrode 6 Processing gas outlet 10 Wafer holder

Claims (1)

[Claims] Claim 1: In a plasma processing apparatus in which a wafer is placed in a vacuum chamber and the periphery of the wafer is pressed with a wafer holder to generate plasma and process the wafer, the wafer holding part of the wafer holder is placed over the entire circumference of the wafer. A plasma processing apparatus characterized in that: