JP3500959B2 - Semiconductor substrate processing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate processing method for processing a semiconductor substrate by etching.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional method for processing a silicon substrate using sandblasting. As shown in FIG. 2B, a resist pattern 2 is formed by laminating a sandblasting resist on the silicon substrate 10 shown in FIG. 2A and exposing and developing a desired pattern.
Form 0.

Next, as shown in FIG. 2 (c), the silicon substrate 10 is etched by sandblasting, and the resist pattern 20 is peeled off, so that the silicon substrate 10 is partially removed as shown in FIG. 2 (d). The shape that has been dug up can be realized.

[0004]

However, in the method of processing a silicon substrate as described above, the depth of the digging due to etching varies within the plane of the silicon substrate 10 or between the silicon substrates 10. Especially 1
In the case of performing deep etching exceeding 00 μm or in the structure of the device, when high processing accuracy is required for the depth of the dug depth and the thickness of the remaining silicon substrate 10, variations in the dug depth due to this etching pose a problem. Become.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method of processing a semiconductor substrate which eliminates the variation in the digging depth due to etching.

[0006]

The invention according to claim 1 is
An intermediate layer made of a material having a higher etching rate than the first and second semiconductor layers is formed between the first semiconductor layer and the second semiconductor layer by the first etching method to form a semiconductor substrate. None, of said first, second semiconductor layer by partially sand blasting one of the semiconductor layers, by digging to reach the intermediate layer, a narrowing the digging stopped in the middle of the intermediate layer, Then, by the first etching method, etching is performed until the dug bottom of the intermediate layer by sandblasting reaches the other semiconductor layer, so that the etching stops at the interface between the other semiconductor layer and the intermediate layer. It is characterized by doing so.

According to a second aspect of the present invention, the first semiconductor layer
Between the second semiconductor layer and the first etching method.
The etching rate is higher than that of the first and second semiconductor layers.
A semiconductor substrate is formed by forming an intermediate layer made of a large material.
Then, one of the first and second semiconductor layers is
Partially ultrasonically processed until reaching the intermediate layer
Dig in and stop this digging in the middle of the middle layer
Then, by the first etching method,
Ultrasonic machining of interlayer
This etching is performed by etching until it reaches
Stopping at the interface between the other semiconductor layer and the intermediate layer
It is characterized by doing so.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the invention described, the first, the second semiconductor layer Siri
It is characterized in that it is made of a single crystal of Con , the intermediate layer is made of a silicon oxide film , and the first etching method is wet etching with hydrofluoric acid .

The invention according to claim 4 is the invention according to claim 1 or 2.
In the invention described above, the first and second semiconductor layers are impure.
The intermediate layer consists of a silicon single crystal with a low substance concentration.
It is characterized in that it is made of a silicon single crystal having a high pure substance concentration, and the first etching method is wet etching with hydrofluoric nitric acid .

[0010]

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a process diagram showing a method for processing a semiconductor substrate according to an embodiment of the present invention. First,
As shown in FIG. 1B, a high-concentration boron layer 2 as an intermediate layer is diffused on the surface of a silicon substrate 1 as a first semiconductor layer as shown in FIG.
Further, as shown in FIG. 1C, a low-concentration single crystal silicon layer 3 as a second semiconductor layer is grown on the high-concentration boron layer 2 by an epitaxial growth method to form a semiconductor substrate.

With respect to this semiconductor substrate, a back surface of the silicon substrate 1 is laminated with a resist for sandblasting, and a desired pattern is exposed and developed.
As shown in (d), a resist pattern 4 is formed.
Next, by sandblasting, a part of the silicon substrate 1 and the high-concentration boron layer 2 thereunder which are not protected by the resist pattern 4 are dug . At this time, this digging is stopped before reaching the low concentration single crystal silicon layer 3 in the middle of the high concentration boron layer 2, but as shown in FIG. surface and between the semiconductor substrate, San
The digging depth by the doblast , that is, the depth of the digging surface 5 has variations.

Here, as shown in FIG. 1F, the resist pattern 4 is peeled off, and as shown in FIG. 1G, only the high-concentration boron layer 2 is selectively etched by hydrofluoric nitric acid (first). Etching method 1). Since the etching in this case is stopped at the interface between the high-concentration boron layer 2 and the low-concentration single-crystal silicon layer 3, the depth of the surface 6 to be etched does not vary, and the depth can be made constant.

In the above embodiment, the first,
Second semiconductor layer, intermediate layer, first etching method, digging
Inclusive method can be various combinations. However, when a silicon oxide film is used instead of the high-concentration boron layer 2, it is impossible to grow the single crystal silicon layer by epitaxial growth. Therefore, the single crystal silicon layer is formed by bonding and polishing, and etching is performed with hydrofluoric nitric acid. Instead, etching with hydrofluoric acid is used. When ultrasonic processing is used instead of digging by sandblasting, the step of forming the resist pattern 4 can be omitted.

Further, in the above-described embodiment, the silicon substrate 1 side is dug by sandblasting or ultrasonic processing.
Although there in silicon, San low concentrations the single-crystal silicon layer 3 side
It may also be dug by blasting or ultrasonic processing .

According to the present embodiment, most of the depth of the semiconductor substrate in the depth direction, that is, the entire silicon substrate 1 and a part of the high-concentration boron layer 2 as the intermediate layer, are dug at high speed by sandblasting or ultrasonic wave. Since the variation in the digging depth is absorbed by the selective etching of the high-concentration boron layer 2, the variation in the digging depth due to the etching is reduced and the finishing accuracy of the digging depth is improved. The processing speed can be improved as well.

[0017]

As described above, according to the present invention, the first and second semiconductor layers are provided between the first semiconductor layer and the second semiconductor layer by the first etching method. A semiconductor substrate is formed by forming an intermediate layer made of a material having a higher etching rate, and one of the first and second semiconductor layers is partially sandblasted or ultrasonically processed ,
Digging until you reach the middle layer,
The intermediate layer is stopped in the middle, and then sandblasting or ultrasonic sounding of the intermediate layer is performed by the first etching method.
This etching is performed by performing etching until the bottom part dug by wave processing reaches the other semiconductor layer.
Since it stopped at the interface between the other semiconductor layer and the intermediate layer, it was possible to provide a method for processing a semiconductor substrate in which the variation in the depth of the dug due to etching was reduced and the finishing accuracy of the dug depth was improved. .

[0018] In the present invention, if such is dug by the sandblasting, it is possible to improve the processing speed.

In the present invention, the above ultrasonic processing is used.
If the digging is performed, the processing speed can be improved and one step can be omitted.

[Brief description of drawings]

FIG. 1 is a process chart showing a method for processing a semiconductor substrate according to an embodiment of the present invention.

FIG. 2 is a process diagram showing a method of processing a semiconductor substrate according to a conventional example.

[Explanation of symbols]

1 Silicon Substrate 2 High Concentration Boron Layer 3 Low Concentration Single Crystal Silicon Layer 4 Resist Pattern 5 Excavated Surface 6 Etched Surface 10 Silicon Substrate 20 Resist Pattern

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-4-61326 (JP, A) JP-A-6-325991 (JP, A) JP-A-6-260378 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01L 21 / 304,21 / 306 H01L 21 / 3063,21 / 308

Claims (4)

(57) [Claims] 1. An intermediate layer made of a material having an etching rate higher than those of the first and second semiconductor layers with respect to the first etching method is provided between the first semiconductor layer and the second semiconductor layer. formed form a semiconductor substrate, the first, of the second semiconductor layer, one of the semiconductor layer than <br/> partially sandblasting, by digging to reach the intermediate layer, the digging
The write is stopped in the middle of the intermediate layer, followed by the first etching process, etching is performed until the bottom dug by <br/> the sandblasting of the intermediate layer reaches the other semiconductor layer, A method for processing a semiconductor substrate, wherein the etching is stopped at an interface between the other semiconductor layer and the intermediate layer. 2. Between the first semiconductor layer and the second semiconductor layer
In addition to the first etching method,
Intermediate made of a material with a higher etching rate than the semiconductor layer
Forming a layer to form a semiconductor substrate, the first and second semiconductors
One of the body layers is partially ultrasonically processed.
Digging until it reaches the intermediate layer,
Stop in the middle of the middle layer, and then the first
Of the intermediate layer by ultrasonic machining
Etching until the recessed bottom reaches the other semiconductor layer
By performing this etching, the etching of the other semiconductor layer is performed.
Is characterized by stopping at the interface between the
Method for processing a semi-conductor substrate that. 3. The first and second semiconductor layers are made of silicon single crystal, and the intermediate layer is made of a silicon oxide film,
3. The method of processing a semiconductor substrate according to claim 1, wherein the first etching method is wet etching with hydrofluoric acid. 4. The first and second semiconductor layers are made of a silicon single crystal having a low impurity concentration, the intermediate layer is made of a silicon single crystal having a high impurity concentration, and the first etching method is wet with hydrofluoric nitric acid. 3. The method for processing a semiconductor substrate according to claim 1, wherein the method is etching.