JP2521904B2 - Method for manufacturing semiconductor device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of manufacturing a semiconductor device in which protrusions on a semiconductor substrate are removed, and in particular, a predetermined fine protrusion is formed by using a positive or negative photoresist. It is a method of removing a part.

[Outline of Invention]

The present invention relates to a method of manufacturing a semiconductor device in which a protrusion on the surface of a vapor phase growth layer formed on a semiconductor substrate is removed by etching, in which a photoresist is formed and only the protrusion is exposed by a predetermined process. By removing the protrusions by means of the above, the predetermined fine protrusions are effectively removed.

[Conventional technology]

Generally, in a process of manufacturing a semiconductor integrated circuit such as a bipolar transistor, an epitaxial growth layer may be stacked on a semiconductor wafer such as a silicon wafer, and the epitaxial growth of silicon is an important process in the process of manufacturing the bipolar transistor.

However, projections of various sizes may be formed in the epitaxial growth layer formed on such a semiconductor wafer. If such a protruding portion is used as it is during the manufacturing process, various problems will occur. For example, when a semiconductor substrate having a protrusion is used as it is in a process such as mask alignment, the protrusion may come into contact with the glass dry plate of the mask, possibly damaging the mask.

Therefore, conventionally, a device (crusher) for crushing a protrusion on a semiconductor substrate in order to remove the protrusion.
Was used.

[Problems to be solved by the invention]

However, due to high integration and miniaturization of semiconductor devices,
The conventional method using the device for crushing the protrusions is becoming insufficient.

That is, when a conventional device for crushing the protrusions is used to flatten the semiconductor substrate, it is possible to crush the protrusions having a height of 10 μm or more to achieve the flatness. With respect to the fine protrusions having the following heights, they cannot function effectively.

On the other hand, in the current semiconductor device manufacturing process,
In order to reduce pattern defects and defects of transistors in integrated circuits, to manufacture highly reliable devices, and to prevent damage to the mask etc. even in the mask aligner, at least the protrusion with a height of 3 μm or more is deleted. There is a need to.

Therefore, in view of the above problems, the present invention has an object of providing a method for manufacturing a semiconductor device, in which fine protrusions generated on the surface of a vapor phase growth layer are removed and a highly reliable semiconductor device can be easily manufactured. And

[Cormorants for solving problems]

The present invention is a method for manufacturing a semiconductor device in which a protrusion on the surface of a vapor phase growth layer formed on a semiconductor substrate is removed by etching, in which a positive photoresist is applied and formed on the entire surface of the vapor phase growth layer, The step of forming the positive photoresist on the protruding portion to be thinner than the area other than the protruding portion, and developing the positive photoresist without exposure to expose only the tip portion of the protruding portion. The process of
The above-mentioned problems can be solved by performing a step of removing the protrusions by etching using the positive photoresist as a mask.

The present invention also provides a method of manufacturing a semiconductor device, wherein a negative photoresist is applied and formed on the entire surface of the vapor phase growth layer, and the negative type photoresist is formed on the protrusions as compared with the area other than the protrusions. A step of forming a thin photoresist,
The negative photoresist is exposed to light under a partial pressure of oxygen controlled according to the residual film rate, and then developed to expose only the tip portion of the protrusion, and the negative photoresist is used as a mask. The above-mentioned problems can be solved by going through the step of removing the protrusions by etching.

[Action]

A predetermined photoresist is used to expose only the protrusion, and the exposed protrusion is removed by etching to planarize the substrate.

For example, when a negative type resist is used as the photoresist, nitrogen is mixed between the glass dry plate and the resist, and the residual film rate at the time of exposure is controlled by adjusting the mixing ratio with oxygen. By control, the resist on the protrusion is removed to expose the protrusion. When a positive resist is used, the resist is left unexposed from the prebaked state, the resist is removed by a phenomenon liquid, and only the protrusions are exposed.

Even with such a fine protrusion, it is possible to easily expose only the protrusion, and since the region other than the protrusion is covered with photoresist, only the protrusion is removed during etching, The substrate can be flattened.

〔Example〕

A preferred embodiment of the present invention will be described with reference to the drawings.

The method for manufacturing the semiconductor device of this embodiment is a method for realizing the removal of fine protrusions in the process of manufacturing the semiconductor device, and is a method capable of removing even fine protrusions of about 3 μm.

 Hereinafter, this embodiment will be described in accordance with steps.

(A) First, as shown in FIG. 1a, a semiconductor substrate 1 having an epitaxial growth layer formed on a silicon wafer is
The protrusion 2 is generated on the surface of the semiconductor substrate 1. Usually, several protrusions 2 are generated per wafer.

(B) As shown in FIG. 1b, a photoresist 3 is formed on the entire surface.
Is formed by coating. Application is a normal spin coating,
The thickness of the photoresist 3 after coating is controlled to about 0.8 μm to 1.0 μm. The photoresist 3 is, for example, a rubber type negative resist, and in this embodiment, is OMR-83 (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.), and JSR-707.
(Nippon Synthetic Rubber Co., Ltd., trade name) may be used.
The photoresist 3 is formed thinner on the protrusion 2 than in the region other than the protrusion 2, and the photoresist 3 in the thin portion is removed in a later process to expose only the protrusion 2. Become.

As described above, the negative resist is used in this embodiment, but a positive resist may be used. When a positive resist is used as described later, the exposure step can be omitted.

(C) As shown in FIG. 1c, the photoresist 3 is exposed through the glass dry plate 4. In the case of a negative resist, photocrosslinking reaction of the resin forming the photoresist 3 proceeds by exposure, but the crosslinking reaction of the resin is inhibited by oxygen gas. Therefore, the glass dry plate 4 is used in close contact with the wafer so that the atmosphere of the photoresist 3 is mixed with nitrogen gas and the partial pressure of oxygen gas is controlled to achieve a desired residual film rate. If the partial pressure of oxygen gas can be controlled, the glass dry plate 4 is unnecessary. The residual film rate is, for example, 0.9 times,
The ratio of the film thickness after development to the initial film thickness.

If the photoresist 3 is, for example, a positive type resist, this exposure step is unnecessary. Therefore, in the pre-baked state, exposure is not performed, and the process proceeds to the next development step.

(D) As shown in FIG. 1D, the photoresist 3 is developed to expose only the protrusion 2. The photoresist 3 remains in regions other than the protrusions 2 and functions as a mask in a later step. Only the protrusion 2 is easily exposed from the above control of the residual film rate. The projection 2 is not necessarily exposed as a whole, and may be exposed enough to be etched. If the glass plate 4 is not used,
Only the protrusion 2 can be exposed with a residual film ratio of 0.7 times.

When the photoresist 3 is, for example, a positive type resist, the resist is partially removed from the surface by a developing solution to expose only the protrusions 2 and leave the resist in regions other than the protrusions 2. To develop.

(E) After exposing the protrusion 2 by development, FIG.
As shown in FIG. 5, etching is performed to remove the exposed protrusion 2. At this time, the photoresist 3 remaining in the region other than the protrusion 2 functions as a mask. The etching is, for example, a RIE method, and a mixed gas of CF ₄ gas and oxygen gas can be used as an etching gas.

(F) After removing the protrusion 2, the photoresist 3 is peeled off as shown in FIG. This is due to sulfuric acid / hydrogen peroxide treatment. The surface 1a of the semiconductor substrate 1 after the photoresist 3 has been peeled off is flattened, and the semiconductor substrate 1 becomes a good substrate with a reduced number of protrusions.

According to the method of manufacturing a semiconductor device of the present embodiment, the fine projections generated on the surface of the vapor phase growth layer can be removed by the above steps, and a flattened semiconductor substrate can be easily formed. In particular, in this embodiment, since the protrusions 2 are exposed by using the photoresist 3, it is possible to sufficiently cope with the protrusions 2 having a thickness of, for example, about 3 μm by adjusting a predetermined film thickness or the like. is there.

When a negative type resist is used as the photoresist 3, the desired protrusion 2 can be exposed by controlling the residual film ratio, and the protrusion can be reliably removed.

Further, when a positive type resist is used as the photoresist 3, the exposure process is unnecessary and the process is shortened.

It is also possible to planarize the photoresist 3 by forming it under a predetermined condition and etching back the entire surface when the thickness of the photoresist 3 on the protrusion 2 is thin.

〔The invention's effect〕

According to the method for manufacturing a semiconductor device of the present invention, a predetermined fine protrusion can be effectively removed by exposing only the protrusion by a predetermined process using a photoresist and removing the protrusion by etching. it can. Therefore, by applying the present invention to the manufacturing process of the semiconductor device, it is possible to surely remove the adverse effect such as the damage of the mask in the mask alignment apparatus. In addition, defects and defects such as patterns can be reduced, and a highly reliable semiconductor device can be easily manufactured.

[Brief description of drawings]

1A to 1F are cross-sectional views for explaining a method of manufacturing a semiconductor device according to the present invention step by step. 1 ... Semiconductor substrate 2 ... Projection 3 ... Negative photoresist 4 ... Glass dry plate

Claims (2)

(57) [Claims] 1. A method of manufacturing a semiconductor device, wherein a projection on the surface of a vapor phase growth layer formed on a semiconductor substrate is removed by etching, wherein a positive photoresist is applied and formed on the entire surface of the vapor phase growth layer. , A step of forming the positive photoresist thin on the projecting portion as compared with the region other than the projecting portion, and developing the positive photoresist without exposing the positive photoresist, and only the tip portion of the projecting portion is developed. A method of manufacturing a semiconductor device, comprising: a step of exposing; and a step of removing the protrusion by etching using the positive photoresist as a mask. 2. A method for manufacturing a semiconductor device, wherein a projection on the surface of a vapor phase growth layer formed on a semiconductor substrate is removed by etching, wherein a negative photoresist is applied and formed on the entire surface of the vapor phase growth layer. , A step of forming the negative type photoresist thin on the protrusions as compared with the region other than the protrusions, and exposing the negative type photoresist on the entire surface under an oxygen partial pressure controlled according to the residual film ratio. A method for manufacturing a semiconductor device, comprising: a step of developing after that, exposing only the tip of the protrusion; and a step of removing the protrusion by etching using the negative photoresist as a mask.