JPH03196622A - Reactive ion etching device - Google Patents

Abstract

PURPOSE:To improve the uniformity between a thick film and a wafer by adding a film thickness measuring function part, an operating function part, and an operation control part and interlocking them so as to measure the etching rate of the film to be etched and calculate the etching time automatically and continuously. CONSTITUTION:A wafer is loaded on an etching function part, and pilot etching is performed under the conditions that the residual film thickness surely becomes thicker than the film thickness D1 that one want to leave finally, and first and second PSG film 32 and 33 are etched by the thickness DELTAd0. Next, residual film thickness 360' is measured, and by an operating function part, pilot-etched film thickness DELTAd0 is calculated, and using the etching rate calculated from the DELTAd0 and the etching time, the etching time required for etching the difference between the residual film thickness d0' measured in advance and the film thickness that one wants to leave finally, that is, additional etching film thickness DELTAd1 is calculated. This way, the etching time is decided by confirming the thickness of the film to be etched and the etching rate this way, so the uniformity of the film thickness can be realized efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reactive ion etching apparatus, and more particularly to a reactive ion etching apparatus having a film thickness measurement function.

[Conventional technology]

Conventional reactive ion etching equipment is not equipped with a film thickness measurement function, so etching is performed for a fixed time. For this reason, methods have been used, such as setting etching conditions such that the etching rate ratio between the film to be etched and the underlying material layer is sufficiently large, or designing the manufacturing process to suit the etching conditions. .

[Problem to be solved by the invention]

In etching using the conventional reactive ion etching apparatus described above, the etching rate ratio between the film to be etched and the underlying material layer is made sufficiently large, and over-etching is performed using the underlying material layer as an etching stopper. When etching is stopped in the middle of the same material layer, for example, when etching back an interlayer insulating layer, the fluctuations in the etching rate and the thickness of the film to be etched will affect the film after etching. This has the disadvantage that it is reflected in the remaining film thickness of the etched film.

For example, consider a case in which a film to be etched with a thickness of 1 μm±0.1 μm is etched under conditions of an etching rate of 50 nm/−±5 nm/win to reduce the thickness of the film to 0.5 μm after etching. The etching time at this time is 10 minutes from the median values of the film thickness of the film to be etched of 1.0 μm and the etching rate of 50 nm/win. In the case of a combination of the minimum film thickness of the film to be etched, 0.9 μm, and the maximum etching rate of 550 nm/win, the film thickness of the film to be etched after etching is the minimum value of 0.35 μm, and similarly, the maximum value is 1 and 1, respectively. 1
In the case of a combination of μm and 450nm/i, 0.65
It becomes μm. Even if the film formation variation of the film to be etched and the variation of the etching rate are each set within the range of ±10%, the film thickness of the film to be etched after etching is 0.5%.
The variation is 5 μm±0.15 μm, which is ±30%.

It is possible to reduce variations in the film thickness after etching to some extent by checking the film thickness of the film to be etched and the etching rate for each operation and determining the etching time. However, this method has drawbacks such as increased man-hours for the operator and decreased throughput. Even with this method, it is realistically impossible to check each wafer. For example, assuming that 100 wafers are checked, there will still be variations between wafers within the minimum unit of 100. become.

[Means to solve the problem]

The reactive ion etching apparatus of the present invention includes a semiconductor etching function section, a bidirectional wafer loader for moving the semiconductor wafer between the film thickness measurement function section and the etching function section, and a film thickness measurement function interface section. an arithmetic function section that processes the measured results and sends a signal to an operation control section; and an operation that controls the operation of the film thickness measurement function section and controls the operation of the etching function section based on the signal from the arithmetic function section. The control unit is configured to include a control unit.

〔Example〕

FIG. 1 is a block diagram of a first embodiment of the present invention.

The single-wafer type reactive ion etching apparatus is mainly composed of a film thickness measurement function section 12 consisting of a film thickness measuring device, an operation control section 14 consisting of a CPU, etc., and an arithmetic function section 15 consisting of an arithmetic circuit, etc. . The etching function section 13 and the film thickness measurement function section 12 are connected by a bidirectional wafer loader 11.
Bidirectional wafer movement is possible. Etching function section 13. Film thickness measurement function section 12. Bidirectional loader-11
The system configuration is such that the operation of the arithmetic function section 15 can be completely controlled by the operation function section 14.

FIGS. 3(a) to 3(d) are cross-sectional views of a semiconductor chip for explaining how to use the first embodiment described above.

First, as shown in FIG. 3(a), polycrystalline silicon 34. The first PSG film 3'2 and the second PSG film 3'2
The wafer on which the SG film 33 has been formed is loaded into the film thickness measuring function section 12, and the first layer of the material to be etched is placed at a desired position.
The film thicknesses d of the PSG film 32 and the second PSG film 33 are measured at, for example, five locations within the wafer, and the calculation function section 14 calculates the average value using a zero-order bidirectional wafer loader 11.

This wafer is loaded into the etching function section 13, and pyro-etching is performed under conditions such that the remaining film thickness is always thicker than the final film thickness dI, as shown in FIG. 3(b).
The first and second PSG films are etched to a thickness of Δd0. Next, the wafer is transferred from the etching function section 13 to the film thickness measurement function section 12 again, the remaining film thickness 36 (dO') is measured, and the calculation function section 15 calculates the film thickness Δd0 etched by pilot etching. , the etching rate is calculated from the Δd0 and the etching time.

The remaining film thickness d0 measured earlier using this etching rate
’ and the final film thickness di that you want to leave, that is, the difference in Figure 3 (C
) The additional etching film thickness (Δd, = do' d
+) Etching time t1 required for etching
Calculate.

Next, the wafer is loaded into the etching function section again and etched for the previously calculated time t1, as shown in Fig. 3(d).
The final remaining film thickness d1 of the film to be etched was obtained as shown in FIG. Here, the measurement of the initial film thickness (do) in FIG. 3(a) and the measurement of the film thickness after pilot etching (do') in FIG. 3(b) are the same. A functional section 12 and a bidirectional wafer loader 24 are provided within a chamber 21 of the etching functional section 13. The etching function section 13, film thickness measurement function section 12, and bidirectional wafer loader 24 are partitioned off by a shutter 27 that can be opened and closed and has a high airtightness. The first point is that these systems have a system configuration in which the entire system is controlled by the operation control section 14A and data processing is performed by the calculation function section 15A.
This is similar to the embodiment.

In this second embodiment, once a wafer is loaded into the chamber 21 and the chamber is evacuated once, the wafer can be moved back and forth between the wafer-side electrode 22 of the etching function section 13 and the wafer stage 25 of the film thickness measurement function section 12. However, this can be carried out without reducing the degree of vacuum in the chamber 21, and there is an advantage that the time required to evacuate the chamber 21 can be relatively shortened.

〔Effect of the invention〕

As explained above, the present invention automatically and continuously adjusts the etching rate of the film to be etched by adding and interlocking a film thickness measurement function section, a calculation function section, and an operation control section to a reactive ion etching apparatus. Since it is possible to measure and calculate the etching time, it is possible to dramatically improve the uniformity of the thickness of the film to be etched between wafers after etching.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the first embodiment of the present invention, FIG. 2 is a schematic diagram of the second embodiment of the present invention, and FIG. 3 is a schematic diagram of the first embodiment of the present invention.
FIG. 3 is a cross-sectional view of a semiconductor chip for explaining the operation procedure of the embodiment. 11...Bidirectional wafer loader-12...
・Film thickness measurement function section, 13... Etching function section, 14° 14A... Operation control section, 15.15A
......Arithmetic function section, 21...Chamber 22...Wafer side electrode, 23...Counter electrode, 24...Bidirectional wafer loader 25・
... Wafer stage, 26 ... Film thickness measuring device, 27 ... Shutter 31 ... Silicon substrate, 32 ... First PSG film, 33・・・
... Second PSG film, 34 ... Polycrystalline silicon, 35 ... Initial film thickness (do), 36 ...
...Residual film thickness (do'), 37... Pilot etching thickness (Δdo), 38... Additional etching thickness (Δd+), 39... Residual film thickness (dl ). Figure 1

Claims (1)

[Claims] A film thickness measurement function section for measuring the thickness of a film formed on a semiconductor wafer, an etching function section for etching the film, and a method for moving the semiconductor wafer between the film thickness measurement function section and the etching function section. a bidirectional wafer loader that moves the wafer to the film thickness measurement section; a calculation function section that processes the measurement results of the film thickness measurement function section and sends a signal to an operation control section; and an operation control section that controls the operation of the etching function section based on signals from the reactive ion etching apparatus.