JPH02185032A - Etching method and etching device - Google Patents

Abstract

PURPOSE:To work only one surface through etching without giving working strain, contamination, etc., to one surface by forming a fluid layer by centrifugal force under the state, in which a wafer is rotated, and supplying a surface to be etched with an etchant. CONSTITUTION:A thin-film-shaped wafer 1 is held at the central section of one surface by a revolution holding section 2, and rotates on its own axis of rotation 30 passing through the center of the wafer. A water current 3 shaped on a surface held by the rotation holding section 2 of the wafer 1 flowes toward the outside by centrifugal force working to the wafer 1. An etchant flow 5 fed to the wafer 1 from an etchant supply section 4 for supplying the other surface of the wafer 1 with an etchant flowes toward the outside by the centrifugal force of the wafer 1 in the same manner as the water current 3, thus preventing the contact of the water current 3 and the etchant flow 5 on the surface of the wafer 1. Consequently, the etchant works only to one surface of the wafer 1, and the wafer is etched. Accordingly, an active layer is not given working strain and contamination, and only a support plate can be machined and etched.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an etching method and an etching apparatus for highly efficient removal processing of a semiconductor substrate.

[Conventional technology]

In recent years, for example, Nikkei Electronics 19g6.10.6
As stated in the paper published on page 76 of the issue titled "Development of SOI technology in which rLSI is polished to a thickness of 0.5 to 1 μm and attached to an insulating plate," LSI fabricated using conventional methods can be machined. Processing is done from the back side by chemical polishing, and only the active layer of the device is taken out and transferred onto the insulating layer.
Silicon on insulator: 5ilicon o
Methods have been developed to fabricate n In5uretor structures. The device structure fabricated by this method has an excellent feature of having fewer crystal defects in the Si single crystal layer compared to SOI structures fabricated by other methods, such as laser annealing, and is suitable for high voltage devices and three-dimensional LSIs. Applications are expected.

FIG. 3 shows schematic diagrams of the steps (a) to (f) in the order of the steps for manufacturing the SOI structure.

First, a device is formed on the active layer 21 on the Si substrate 20 (FIG. 3(a)), and then a Si single crystal support plate 23 is bonded to the upper surface of the active layer 21 using the adhesive 22 (see FIG. 3(a)). After that, the Si substrate 20 is removed by rough polishing and mechanochemical polishing, leaving only the active layer 21 (FIG. 3(c)), and an adhesive 24 is applied to the back surface of the active layer 21. After removing the supporting plate 23 by rough polishing and mechanochemical polishing (FIG. 3(e)), the adhesive 22 remaining on the active layer 21 is removed by plasma treatment. The SOI structure is completed by removing it by means such as ashing (FIG. 3(f)).

[Problem to be solved by the invention]

In the SOI structure forming method as described above, as shown in FIG.
In the support plate removal process, the support plate 23 is removed by rough polishing by lapping and mechanical/chemical polishing, but lapping takes several hours and may cause processing distortion and contamination to the device that has already been thinned and completed. The problem is that there is gender. Further, when removing the support plate by etching, since the support plate 23 and the substrate 25 are made of the same material (Si single crystal), it is difficult to process only the support plate 23 and leave the other parts unprocessed.

At this time, if one of the support plate 23 and the substrate 25 is made of a material other than the SL single crystal, selectivity can be imparted by etching, but since the coefficients of thermal expansion of the materials are different, the active film is thinned by heating in the bonding process. A problem arises in that the layer 21 expands and contracts.

SUMMARY OF THE INVENTION An object of the present invention is to provide an etching method and an etching apparatus that can eliminate the above-mentioned conventional drawbacks and process only the support plate with high efficiency without causing processing distortion or contamination to the active layer.

[Means to solve the problem]

In the etching method of the present invention, a non-etching fluid is supplied to one surface of the wafer to form a fluid layer while the wafer is rotated about the wafer center axis, and the other surface of the wafer (to be etched) is supplied with a non-etching fluid to form a layer of the fluid. The wafer material is processed by supplying an etchant having an etching property to the wafer material.

The etching apparatus of the present invention includes a holding/rotating mechanism that holds the center of one surface of a wafer and rotates the wafer around a central axis, and a fluid supply that supplies fluid to the holding surface to form a layer of fluid. and an etchant supply mechanism for supplying an etchant having etching properties to the wafer material to the other surface of the wafer.

[Effect]

The present invention solves the problems of the prior art by adopting the above-described configuration. That is, while the wafer is rotating, a non-etching fluid is supplied to one surface, a layer of fluid is formed from the center to the outside by centrifugal force, and an etchant is applied to the other surface (the surface to be etched). By supplying the etchant, it is possible to perform etching without the etchant going around to the back side. As a result, it becomes possible to perform etching on only one side without causing processing distortion or contamination to the other side.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram for explaining the etching method of the present invention. Reference numeral 1 denotes a thin film-like wafer in the state shown in FIG. 3(d), which is held at the center of one side by a rotating holding section 2 and is rotating about a rotating shaft 30 passing through the center of the wafer. 3 is a water flow formed on the surface of the wafer 1 held by the rotating holding unit 2, which flows outward due to the centrifugal force acting on the wafer 1; 4 is for supplying etchant to the other surface of the wafer 1; Since the etchant flow 5 supplied to the wafer 1 from this etchant supply section flows outward due to the centrifugal force of the wafer 1 like the water flow 3, the water flow 3 and the etchant flow 5 are connected to the wafer 1. There is no contact with the surface. Therefore, the etchant acts on only one side of the wafer 1 to perform etching.

FIG. 2 is a sectional front view showing an embodiment of the etching apparatus of the present invention.

In this device, a shaft 7 connected to a vacuum chuck 6 is connected to a motor 8.
and a holding/rotating mechanism in which a decompression case 10 equipped with an exhaust pipe 11 is connected to a T-shaped hole 7 provided in the shaft 7, and a water supply hole 1.
4, and an etchant supply mechanism including an etchant tank 15, an etchant pump 16, and an etchant pipe 17. The thin film wafer 1 in the state shown in FIG. 3(d) is held by the vacuum chuck 6 at the center of the lower surface with the substrate 25 side (see FIG. 3) as the lower surface. The vacuum chuck 6 is connected to a shaft 7 and rotated by a motor 8 to rotate the wafer 1 . A T-shaped hole 9 is provided in the center of the shaft 7.
is connected to an external vacuum pump (not shown) via a decompression case 10 and an exhaust pipe 11. Shaft 7 and decompression case 10
Since the space between the two wafers has an airtight and rotatable structure, the rotating wafer 1 can be held by a vacuum chuck. Reference numeral 12 denotes a water supply case installed on the outer periphery of the shaft 7 in an airtight and rotatable structure. Water is supplied to the back surface of the wafer 1 from the water supply hole 14, and a layer of water is formed on the back surface of the wafer 1 by centrifugal force. An etchant tank 15 supplies etchant to the surface of the wafer 1 via an etchant pump 16 and an etchant pipe 17, and causes the etchant to act on the entire surface of the wafer 1 by centrifugal force caused by the rotation of the wafer 1.

At this time, since there is a flow of water outward from the center of the wafer on the back surface of the wafer l, the etchant processes only the surface without going around. Reference numeral 18 denotes a tray for collecting waste liquid, and the waste liquid is discharged to the outside through a waste liquid pipe 19.

Using an etching apparatus with such a configuration, for example, HF (49%):HNO3 (70%):N is used as an etchant.
20=65:20:15 (weight ratio), liquid temperature=20℃
When used to remove the support plate in the state shown in FIG. 3(e) during the formation of the SOI structure, the thickness of the support plate was 500 μm in 14 minutes.
The support plate (plane orientation (100>)) can be removed,
It used to take 3 to 4 hours for removal by lapping and mechanical/chemical polishing, but now it is possible to significantly shorten the time.

Furthermore, since there is an adhesive layer between the support plate and the active layer, processing automatically stops at the interface between the adhesive layer of the support plate.

In this example, a method using a vacuum chuck was used to hold the wafer 1, but if the same effect can be obtained, other holding methods such as adhering with wax or fixing with adhesive tape may also be used. Etchant supply method Although a method is shown in which the etchant is supplied concentratedly to the center of the wafer, if it can be supplied to the entire surface of the wafer, it may be supplied from multiple locations or in the form of a shower. , N20 was used, but it is also possible to use other etchants that have etching properties for the support plate material. Further, the fluid supplied to the non-processed surface may be any fluid other than water, such as a gas such as N2 gas, as long as it can form a layer of non-etching fluid on the non-processed surface.

〔Effect of the invention〕

As explained above, according to the etching method and etching apparatus of the present invention, the support plate can be removed with high efficiency without straining the thinned device layer. Extremely effective.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining the etching method of the present invention, FIG. 2 is a cross-sectional front view showing an embodiment of the etching apparatus of the present invention, and FIG. 3 is a schematic diagram of the method for manufacturing a thin layered SOI structure. It is a diagram. 1... Wafer, 2... Rotating holding part, 3... Water flow,
4... Etchant supply unit, 5... Etchant flow, 6... Vacuum chuck, 7... Shaft, 8... Motor, 9... T-shaped hole, 10... Decompression case, 11 ...
Exhaust pipe, 12... Water supply case, 13... Water supply pipe, 1
4...Water supply hole, 15...Echant tank, 16
... Etchant pump, 17 ... Etchant pipe, 18 ... Receiver is dish, 19 ... Waste liquid pipe, 20 ... 8
1 substrate, 21...active layer, 22...adhesive, 23...support plate, 24...adhesive, 5...substrate.

Claims (2)

[Claims] (1) While rotating the wafer around the wafer's central axis, a non-etching fluid is supplied to one side of the wafer to form a fluid layer, and then the other side of the wafer is An etching method characterized by supplying an etchant having etching properties to the wafer material. (2) A holding/rotating mechanism that holds the center of one surface of the wafer and rotates the wafer about its central axis, a fluid supply mechanism that supplies fluid to the holding surface, and a fluid supply mechanism that supplies fluid to the other surface of the wafer. An etching apparatus comprising: an etchant supply mechanism that supplies an etchant with etching properties to a wafer material.