JP3212756B2 - Dry etching 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 method for dry etching a semiconductor substrate, an optical substrate and the like.

[0002]

2. Description of the Related Art Generally, there are a wet etching method and a dry etching method as a technique for finely etching patterns of various thin film materials constituting a semiconductor circuit.

At present, as the integration density of semiconductor circuits has been improved, a dry etching method, which is a more accurate etching technique, has been widely used.

FIG. 7 shows an argon ion etching method called ion milling as an example of a conventional dry etching method. An element formation region 36 is formed on the entire surface of the semiconductor substrate 2. The semiconductor substrate 2 is provided with a desired resist pattern, and the surface of the semiconductor substrate 2 is provided with a surface (etched surface) 10 on which the resist 4 is not applied and a surface (mask surface) 1 on which the resist 4 is applied.
4 are provided. FIG. 8 is a partially enlarged view of FIG.

First, a high energy argon ion beam 8 is generated, and the argon ion beam 8 is caused to collide with the entire surface of the semiconductor substrate 2 at a predetermined angle.

On the etching surface 10, the argon ion beam 8 collides with the atoms 6 in the element forming region 36,
The atoms 6 fly out of the semiconductor substrate 2. Then, the atoms 6 are successively ejected by the argon ion beam 8, and the atoms 6 are stripped to the bottom surface 12 of the etching surface. On the other hand, the mask surface 14 is protected by the resist 4 and is not etched. That is,
The semiconductor substrate 2 is etched according to a desired resist pattern. Thereafter, the resist 4 is removed by an alkaline aqueous solution or the like.

Conventionally, a semiconductor substrate has been etched by such a dry etching method.

[0008]

However, the conventional dry etching method has the following problems.

Although the etching surface of the semiconductor substrate 2 is etched well up to the bottom surface 12, irregularities may occur in the etched cross section 16 below the end surface of the resist 4. This is due to the following reasons.

As shown in FIG. 9, it is difficult to form the end face of the resist 4 without unevenness (101 shown in the figure) in the mask work. Therefore, when the argon ion beam 8 collides with the resist 4, it is incident on the end face of the resist 4 along the irregularities, so that the irregularities (illustration 103) are transferred to the etching section 16 as they are. Also, in the case where foreign matter is included in the resist 4, irregularities are similarly transferred to the etched cross section 16.

Therefore, for example, as shown in FIG.
In the semiconductor laser device 5, when the mirror surface is required for the etched cross section of the semiconductor device, such as when the end surface of the light emitting portion 27 of the device forming region 36 is required to have the mirror surface,
There is a problem that it is difficult to use a dry etching method.

Conventionally, when the reflection surface of the semiconductor laser element 5 is formed, for example, as shown in FIG. 10B, a scratch K is formed on the surface of the semiconductor substrate 2 for each semiconductor laser element 5 by glass cutting. After that, the semiconductor substrate 2 is broken in a direction in which the semiconductor substrate 2 is easily broken by applying bending stress such as a roller, and the mirror surface of the fracture surface 26 is obtained. However, such a method has a problem that the cleavage operation is complicated and lacks certainty.

An object of the present invention is to provide a dry etching method capable of solving the above-mentioned problems and easily and surely making an etched cross section of a substrate to be etched into a mirror surface.

[0014]

According to a first aspect of the present invention, there is provided a dry etching method, wherein a substrate to be etched is irradiated with a directional ion beam to etch an etching surface excluding a mask surface on the substrate to be etched. In the dry etching method,
The ion beam is made to pass substantially parallel to the etching cross section of the mask surface, and the angle at which the ion beam passing through the etching cross section is incident on the substrate to be etched is changed. And

[0015]

According to the dry etching method of the present invention, the ion beam is made to pass substantially parallel to the etching section, and the angle of incidence of the ion beam is changed while keeping the ion beam and the etching section parallel. I try to make it. Therefore, even if the resist end face has irregularities, it is possible to prevent the irregularities from being produced in the etched cross section.

[0016]

FIG. 2 shows a dry etching method for an etched (semiconductor) substrate 2 according to an embodiment of the present invention. An element formation region 36 is formed on the entire surface of the semiconductor substrate 2. In the x direction, a plurality of etched surfaces 10 (10
_1, 10 _2, 10 _3, a plurality of mask surfaces 14 ...) and the resist 4 is applied (14 _1, 14 _2, 14 _3, ...) are provided alternately. The semiconductor substrate 2 rotates in the P and Q directions about a rotation axis J located in the x direction and substantially at the center of the semiconductor substrate 2 in the y direction.

When the ion beam collides with the semiconductor substrate 2, the etching surface 10 excluding the mask surface 14 is etched. FIG. 1 shows a partial perspective view of FIG. FIG. 1A shows a state before etching, and FIG. 1B shows a state after etching by this dry etching method. As shown in FIG. 1a, for example, unevenness is generated on the end surface of the resist 4 _3.

FIG. 3 is a sectional view showing a boundary between the etching surface 10 and the mask surface 14 in FIG. Thus in the figure, the resist 4 (4 _1, 4 _2, 4 _3, ...) end surface and etching section 16 (16 _1, 16 _2, 16 _3, ...) and are crack table.

First, the ion beam is applied to the etching section 16.
1a, the semiconductor substrate 2 shown in FIG.
Etched surface ₁₀₃ of and to collide with the resist 4 _3. The incident angle of the ion beam is substantially perpendicular to the rotation axis J.

As shown in FIG. 3, the semiconductor substrate 2, since is rotatable (in the direction perpendicular to the paper surface) rotational axis J P around a, in direction Q, in the etching section 16 _3, the ion beam The incident angle with respect to the semiconductor substrate 2 is α
゜ to γ ゜. In this example, this angle of incidence is 4
The angle is in the range of 5 ° to 135 °.

[0021] Therefore, the ion beam strikes while changing the incident angle be substantially parallel to the etching section 16 _3. Thus, the ion beam, since the around to the etching section 16 ₃ immediately under the resist 4 ₃ end surfaces, even if there is unevenness on the resist 4 ₃ end surfaces, etch profile 16 _3, the etching state is not uneven as shown in Figure 1b Is done. Thus the etching section 16 ₃ is a mirror. The resist 4 ₃ left is removed by an alkaline aqueous solution.

As described above, according to this dry etching method, the unevenness of the etched section 16 due to the transfer of the unevenness of the end face of the resist 4 does not occur conventionally. Is realized.

By the way, when the ion beam collides with the resist 4, as shown in FIG. 4A, the end face is etched and the end face of the resist 4 may recede (see FIG. 20).
1). As a result, the etched section 16 may be inclined at an angle θ °. Therefore, the etching cross section 16
When verticality is required, the etched section 16 is previously inclined by θ ° as shown in FIG. 4B. Thereby, the etching section 16 is vertically etched. In order to make the etched section 16 a mirror surface, as shown in FIG. 4C, V, V are set substantially parallel to the etched section 16 inclined at the angle θ ° and about the rotation axis G inclined at the angle θ °. It is necessary to change the incident angle of the ion beam in the W direction.

Further, by this dry etching method, it is possible to improve the efficiency of inspecting characteristics such as electric characteristics and light emission characteristics of a semiconductor element which requires mirror surface properties. FIG. 5 shows a method for inspecting the semiconductor laser device 5. As shown in FIG. 5A, a probe card 44 having a photodiode 40 and a probe 42, a measurement circuit 46, a light shielding device 48, and an inspection stage 50 are used in this method.

First, when the semiconductor substrate 2 is dry-etched, as shown in FIG. 5B, the etching surface 24 is etched deeper than the device forming region 36 of the semiconductor laser device 5. Thus, the semiconductor laser element 5 ₁ of the element forming region 36 ₁ and the semiconductor laser element 5 _second element forming region 3
6 ₂ in a state of being separated from the. However, each semiconductor laser element 5 itself is not separated from the semiconductor substrate 2. In this state, the electrode 33 is placed on the surface of the semiconductor laser element 5.
However, an electrode 34 is provided on the bottom of the semiconductor substrate 2.

Next, the semiconductor substrate 2 is placed on the inspection stage 50 which is shielded from light by the light shielding device 48. The electrode 34 is connected to a measurement circuit 46 via an inspection stage 50. The probe 42 is connected to a measuring circuit 46. When the probe 42 is in contact with the electrode 33 ₁ of the semiconductor laser device 5 _1, the semiconductor laser element 5 ₁ is energized, the laser is emitted from the light emitting unit 27 _1. Then, in a state with its photodiode 40 to the light-emitting unit 27 _1, the measuring circuit 46, the laser intensity variation of the scattered light at the time of changing the current is measured. Thus, the characteristics of the semiconductor laser element 5 ₁ is inspected. Next, the probe 42 is brought into contact with the electrode 33 ₂ of the semiconductor laser element 5 _2, likewise characteristic of the semiconductor laser element 5 ₂ is examined.
As described above, the semiconductor laser elements 5 are respectively inspected on the semiconductor substrate 2. Thereby, as compared with the case where the semiconductor laser element is inspected in a state of discrete chips, the trouble of rearranging the chips and the like are omitted, and the inspection efficiency is improved.

FIG. 6 shows a dry etching method for the optical component 9 according to another embodiment. In this case, the etching section 60 of the optical component 9 (60 _1, 60 _2, 60 _3, 60 ₄₎ and a predetermined angle (e.g. 45 °) is etched so as to mirror. For example, by rotating the optical component 9 in the etching section 60 within ₁ about a rotation axis K of the same angle as the etching section 60 _1, the ion beam is impinging on the etching section 60 ₁ under the resist 64 end surface. Thus, even if there are irregularities in the resist 64 the end face can be etched section 60 ₁ a mirror surface. Similarly, by rotating the optical component 9 about the rotation axes L, M, and N, respectively, the etched sections 60 ₂ , 60 ₃ , and 60 _{4 are obtained.}
Can be mirrored.

Although the incident angle of the ion beam is changed by rotating the semiconductor substrate in this embodiment, the incident angle of the ion beam itself may be changed without rotating the semiconductor substrate.

In this embodiment, the dry etching method is applied to ion milling.
(Electron cyclotron resonance) The present invention may be applied to a plasma etching method.

[0030]

According to the dry etching method of the present invention, the ion beam is allowed to pass substantially parallel to the target etching section, and the ion beam is incident while keeping the angle between the etching section and the ion beam constant. To change the angle at which they do. Therefore, even if the resist end face has irregularities, it is possible to prevent the irregularities from being produced in the etched cross section. Thereby, the erosion (semiconductor)
It is possible to provide a dry etching method for easily and surely making the etched section of the substrate a mirror surface.

[Brief description of the drawings]

FIG. 1 is a partial perspective view showing a dry etching method for a semiconductor substrate according to one embodiment of the present invention.

FIG. 2 is a diagram illustrating a method of dry etching a semiconductor substrate according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view of the above-described dry etching method for a semiconductor substrate.

FIG. 4 is a diagram illustrating correction of vertical etching.

FIG. 5 is a view showing an inspection method after performing the above-described dry etching method for a semiconductor substrate.

FIG. 6 is a diagram illustrating a dry etching method for an optical component according to another embodiment.

FIG. 7 is a diagram showing a conventional dry etching method.

FIG. 8 is a diagram showing a partial perspective view of a conventional dry etching method.

FIG. 9 is a perspective view showing unevenness of an etched cross section in a conventional dry etching method.

FIG. 10 is a diagram showing a conventional method for making an etched cross section a mirror surface.

[Explanation of symbols]

 2 ... Semiconductor substrate 4 ... Resist 10 ... Etching surface 14 ... Mask surface 16 ... Etching cross section J ... Rotating axis

Claims (1)

(57) [Claims] 1. A dry etching method for irradiating a substrate to be etched with a directional ion beam to etch an etching surface of the substrate other than a mask surface, wherein the substrate to be etched is firstly etched . Tilted around the rotation axis of
And further perpendicular to the first rotation axis and in the plane of the substrate to be etched.
The substrate to be etched is separated from its lead by a certain second rotation axis.
Rotated within a range of 45 ° to 135 ° with respect to the vertical direction
A dry etching method characterized by irradiating an ion beam while performing the etching.