JPH03246942A - Production of semiconductor substrate - Google Patents

Abstract

PURPOSE:To flatten and smooth a substrate surface by forming and baking a resin layer after etching a baked resin layer. CONSTITUTION:On a semiconductor substrate 101, resin(polyimide) 102 is formed by a spin coater and baked at 200 deg.C for one hour to be softened. Then, the substrate is etched by O2 plasma and the top of a projecting part is completely exposed. At this time, the resin 102 in a recessed part remains 1.6mum below the top of the projecting part. A resin layer is formed on the substrate 101 and the level difference of 1.6mum is filled. Then, the layer is baked to be flatten allowing 0.2mum level difference. Thus, the smooth substrate surface is flattened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor substrate, and particularly to improvement in planarization of the surface of a semiconductor substrate.

[Prior Art] Conventionally, as a method for flattening the surface of a semiconductor substrate, there is a technique of forming a resin layer to flatten surface irregularities and undulations. Widely used.

As a method for forming the resin layer, there is a method of coating and forming using a roll coater, a spinner, printing, etc.

If the uneven steps or the spaces between the steps become large, the planarization becomes more difficult, but as in Japanese Patent Application Laid-open No. 1-188801, a method of flattening by filling the substrate surface with resin has been proposed. . This method achieves flatness over the entire surface, and is called smoothing to distinguish it from flattening the minute portions.

[Problems to be Solved by the Invention] However, the resin undergoes thermal deformation during firing due to the volatilization of the solvent or the characteristics of the resin itself.

For this reason, even if a filled and flattened coating is performed, after baking, deformation occurs depending on the coating amount reflecting the unevenness of the semiconductor substrate, making flattening difficult. Furthermore, since a jig for filling and coating is run, the shape of the substrate to be flattened is limited, and a jig specifically for that substrate must be created. Filling application is
Although this is an effective planarization method when there are large uneven steps or spaces between steps on the substrate surface, the workability and reproducibility of coating are not necessarily good, and furthermore, the physical contact between the jig and the semiconductor substrate may be difficult. may cause damage to the substrate surface.

Normally, a method is used in which a resin layer is formed by stacking it several times and then flattened, but if the uneven steps or the spaces between the steps become large, the resin layer will be formed to follow the surface shape of the substrate, resulting in flattening. The film must be extremely thick, which requires a large amount of resin and requires a large number of manufacturing steps. Moreover, the unevenness and waviness of the surface due to the thermal deformation of the resin described above cannot be easily eliminated, making it difficult to flatten the surface.

The present invention is intended to solve these conventional drawbacks, and its purpose is to flatten the unevenness of the surface of a semiconductor substrate with a simple manufacturing process, and to provide a semiconductor that can be uniformly smoothed over the entire surface. A method for manufacturing a substrate is provided.

[Means for Solving the Problems] A method for manufacturing a semiconductor substrate of the present invention includes: a) forming a resin layer on the semiconductor substrate; and b)
C) etching the fired resin layer by a predetermined amount; d) forming a resin layer on the etched resin; e) firing the resin layer. It is characterized by consisting of.

[Example] Hereinafter, an example of the present invention will be described in detail using the drawings.

In the example, a semiconductor substrate was used in which unevenness was arranged at regular intervals with a pitch of about 10 μm and had a step difference of about 4 μm in the depth direction.

First, polyimide is applied onto this substrate using a spin coater.

Next, the polyimide is baked at 200° C. for about 1 hour to completely cure it. After firing, the polyimide layer changes into a shape as shown in FIG. 1(a). At this time, the concave portion is almost filled with polyimide, and the difference in level from the convex portion is about 1.6 μm.

Next, polyimide is etched using 02 plasma, and the etching is terminated when the upper surface of the convex portion is completely exposed as shown in FIG. 1(b). Since etching uniformly removes a predetermined film thickness over the entire surface, the polyimide in the concave portion should remain at a height of 1.6 μm below the top surface of the convex portion.

Next, a polyimide layer is formed again on this substrate.

This is essentially the same as filling a 1.6 μm step.

After firing, it will look like Figure 1 (c), with a step difference of approximately 0°2 μm.
flattened to.

When further planarization is desired, etching is performed in the same manner using 02 plasma, and polyimide is applied to achieve almost complete planarization.

In another embodiment of the present invention, by first applying polyimide twice, the level difference after firing is 0. 6μ
Shrinks to m. At this time, the polyimide film thickness is about 8 μm. After that, etching is carried out in the same manner as in the embodiment, and polyimide is applied, thereby flattening the level difference to 0.1 μm or less. However, care must be taken because if the film thickness to be etched becomes large, it may not be removed uniformly and the amount of etching may become uneven.

In this way, it is possible to easily flatten not only a minute portion of the surface of the semiconductor substrate but also the entire surface of the substrate. A substrate with a rectangular shape different from that used in this example can also be flattened in the same way, and if the viscosity of the resin is adjusted appropriately according to the surface shape of the substrate, there is no need for repeated coatings and the manufacturing process can be done more easily. On the other hand, by repeating the coating and etching in this embodiment, almost complete planarization and smoothing can be achieved.

As described above, the present invention makes it possible to obtain a semiconductor substrate with a smooth surface without being limited by the shape of the semiconductor substrate or the minute surface shape.

Although polyimide was used as the resin in the examples of the present invention,
Even when other resins are used, the present invention is effective because flattening can be achieved by the method of the present invention.

Further, even when the semiconductor substrate surface has a shape other than the rectangular shape of the embodiment of the present invention, the flattening effect can be achieved and the present invention is effective.

Furthermore, the present invention is effective even in the manufacture of semiconductor devices having a multilayer structure, since planarization can be performed by the method of the present invention.

[Effects of the Invention] As described above, according to the present invention, a smooth semiconductor substrate can be obtained by a simple method without being affected by the surface shape of the semiconductor substrate. This allows easy formation and processing of transparent electrodes on the substrate. Furthermore, since the surface is flat, it can be processed as an element constituting a multilayer structure.

Another effect of this embodiment is that it is possible to create a panel with a uniform gap, so it can be applied as a photoconductor used in liquid crystal panels and the like.

[Brief explanation of drawings]

FIGS. 1(a) to 1(c) are cross-sectional views of steps in one embodiment of the present invention. 2 More than semiconductor substrate resin

Claims (1)

[Claims] A method for flattening unevenness and undulations on the surface of the semiconductor substrate by forming a resin layer on the semiconductor substrate, comprising: a) forming a resin layer on the semiconductor substrate; b)
c) etching the fired resin layer by a predetermined amount; d) forming a resin layer on the etched resin; e) firing the resin layer; A method for manufacturing a semiconductor substrate, comprising: