JPH0543289B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a thin film decomposition method for decomposing a thin film such as an oxide film formed on a semiconductor substrate, and a method for implementing the method. It relates to a device for.

(Prior art) In a thin film such as an oxide film formed on a semiconductor substrate,
It is well known that when impurities such as Na, K, and Fe are contained, even if the amount is extremely small, it greatly affects the electrical characteristics of a semiconductor device. Therefore, in order to improve the electrical characteristics of the device, it is necessary to accurately grasp the content of these impurities and to suppress the incorporation of the impurities as much as possible when forming the thin film.

Conventionally, a thin film decomposition apparatus having the structure shown in FIG. 2 has been used to decompose a thin film on a semiconductor substrate and measure the impurity content therein.

In FIG. 2, reference numeral 1 denotes an airtight container with a lid 1a, and inside the airtight container 1 are a beaker 3 containing a hydrofluoric acid solution 2, and a wafer carrier 5 containing a semiconductor substrate 4 in an upright state. , a support stand 6 for supporting the wafer carrier 5, and a decomposition liquid receiving tray 7 supported by the support stand 6 and disposed directly below the wafer carrier 5. In order to decompose the thin film 8 on the semiconductor substrate using this device, it is left at room temperature in the state shown in the figure. By standing, the hydrofluoric acid vapor generated from the hydrofluoric acid liquid 2 in the beaker 3 gradually decomposes the thin film 8.
The decomposition liquid 9 becomes droplets and accumulates in the decomposition liquid receiver 7, so after a predetermined time, the lid is opened and the wafer carrier 5 is taken out, and the decomposition liquid in the decomposition liquid receiver 7 is collected by a micro-pillet. The amount of impurities in the thin film was measured by analyzing the liquid using a flameless atomic absorption spectrometer.

However, according to the conventional thin film decomposition device,
Because the semiconductor substrate is placed vertically on the wafer carrier 5 and exposed to hydrofluoric acid vapor,
The thin film 8 on both the front and back surfaces of the semiconductor substrate 4 will be decomposed. In addition, after the decomposition is completed, the decomposition liquid becomes droplets,
Most of it collects in the decomposition tray, but a small amount remains on the semiconductor substrate 4. Therefore, it had to be collected using a micropilette, which was inefficient and also caused contamination of the decomposition solution.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an efficient method and apparatus for decomposing a thin film of a semiconductor substrate, which can decompose only a thin film on one side of a semiconductor substrate. With the goal.

[Structure of the invention] (Means and effects for solving the problems) The first invention of the present application evaporates a hydrofluoric acid solution in a closed container and exposes only one side of a horizontally installed semiconductor substrate to the vapor. This is a thin film decomposition method for a semiconductor substrate, which is characterized in that the thin film on one side of the substrate is thereby decomposed and a decomposition liquid is collected on the substrate.

The second invention of the present application includes a sealed container, a hydrofluoric acid tank provided in the sealed container, and a semiconductor substrate provided in the same sealed open container, which is installed horizontally and exposes only one side of the substrate. 1 is a thin film decomposition apparatus for semiconductor substrates, characterized by comprising a storage member. According to the present invention, only the thin film on one side of the semiconductor substrate can be efficiently decomposed.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1a to 1c. Here, figure a is a front view, figure b
is a side view, and c is a plan view. Incidentally, the same members as those in the prior art are denoted by the same reference numerals, and the explanation thereof will be omitted, and only the storage member will be explained.

11 in the figure is a storage member provided within the closed container 1. This storage member 11 includes, for example, four racks 13 having a plurality of grooves 12a in the vertical direction,
It is composed of two supporting members 14 having grooves 12b arranged at predetermined positions between these racks 13, and a wafer stand 15 that is slidably accommodated in the grooves 12a of the racks 13 and the grooves 12b of the supporting members 14. be done. A semiconductor substrate (wafer) is mounted on the wafer table 15.
A stepped portion having the same shape as the wafer 16 is provided, and the wafer 16 is placed on this stepped portion. Here, wafer 1
6 is placed on the wafer 15 with one side on which the semiconductor thin film is formed facing up.

Next, the method of the present invention will be explained.

First, the wafer 16 with the wafer 16 placed thereon is placed on the wafer stand 15 with the side to be disassembled facing up, and is slid into the groove 12 of the rack 13. Next, a plurality of wafer stands 15 on which wafers 16 are placed
The rack 13 containing the following is placed in the closed container 1 shown in FIG. Next, the beaker 3 in the airtight container 1
Hydrofluoric acid 2 is stored in the container, and the lid 1a of the airtight container 1 is closed to seal it. Here, when left for several hours at room temperature, the hydrofluoric acid 2 evaporates and fills the airtight container 1.
The filled hydrofluoric acid 2 and vapor touch the upper surface of the wafer 16 through the gap between the racks 13, and the thin film on only one side of the wafer 16 is decomposed. The decomposition liquid then collects at the center of the wafer 16. When the thin film is completely decomposed, take out the rack 13 from the airtight container 1,
The wafer stand 15 is pulled out, and the decomposed liquid on the wafer 16 is directly applied to a measuring instrument such as a frameless atomic absorption spectrometer and analyzed.

However, according to the method of the present invention, only one side of the wafer 16 is exposed to the vapor of the hydrofluoric acid solution to decompose the thin film on one side of the wafer 16, so there is no need to collect the decomposition liquid compared to the conventional method, and the process of disassembly and work is reduced. time can be significantly reduced. In addition, contamination due to collection work can be prevented. Furthermore, it becomes possible to separate and measure thin films on both the back and front surfaces of the wafer 16.

Further, the thin film decomposition apparatus for semiconductor substrates according to the present invention has a structure in which a wafer 16 is placed horizontally in a closed container 1 and a storage member 11 is provided that exposes only one side of the wafer 16 to the vapor of a hydrofluoric acid solution. Therefore, if the thin film formed on the wafer 16 is decomposed using this apparatus, the same effect as described above can be obtained.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to provide a method and apparatus for decomposing a thin film of a semiconductor substrate, which can efficiently decompose only a thin film on one side of a semiconductor substrate.

[Brief explanation of the drawing]

1A is a front view of a storage member of a semiconductor substrate thin film decomposition apparatus according to an embodiment of the present invention, FIG. 1B is a side view of FIG. 1A, FIG. 1C is a plan view of FIG. The figure is an explanatory diagram of a conventional thin film decomposition apparatus for semiconductor substrates. DESCRIPTION OF SYMBOLS 1... Airtight container, 2... Hydrofluoric acid, 3... Beaker, 11... Storage member, 12a, 12b...
Groove, 13... Rack, 14... Support material, 15...
Wafer stand, 16...wafer.

Claims (1)

[Claims] 1. A hydrofluoric acid solution is evaporated in a closed container, and only one side of a horizontally placed semiconductor substrate is exposed to the vapor, thereby decomposing a thin film on one side of the substrate and dissolving the decomposed liquid onto the substrate. A method for decomposing thin films of semiconductor substrates, characterized by collecting . 2. Equipped with a sealed container, a hydrofluoric acid tank provided in the sealed container, and a storage member provided in the sealed container for horizontally placing a semiconductor substrate and exposing only one side of the substrate. A thin film decomposition device for semiconductor substrates, characterized by: