JPS6030101B2 - Pattern formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a pattern by selectively embedding a metal or an insulating material in a recess of an arbitrary shape formed in a substrate, and its feature is that It has a two-layer structure consisting of a type photosensitive resin and a layer made of a material that does not dissolve in solvents of the same positive type photosensitive resin.

First, a conventional example will be explained. A pattern is formed on a semiconductor substrate or an insulating substrate using a photoetching technique, and an impurity is diffused using a diffusion technique to form a passive element or an active element having desired characteristics on the semiconductor substrate or an insulating substrate. It is possible to form a so-called IC, a pseudo-1, etc. Attempts have been made to construct ICs and LSIs with such features by selectively embedding metal or insulating layers only in recesses provided in the semiconductor substrate or insulating substrate. For example, as shown in FIG. 1, a recess 2 is formed in a substrate 1 (FIG. 1a), and an insulating layer or a metal layer 3 is formed by means such as sputtering or vapor deposition.
If the insulating layer or metal layer 3 of the convex portion 4 is removed as shown in FIG. 1b), only the metal or insulating layer 3 buried in the recessed portion 2 remains as shown in FIG. 1c. An example of the application of the pattern formed in this manner is insulation isolation as shown in FIG. For example, Si0 is applied to the semiconductor substrate 6 having the epitaxial growth layer 5 to a depth reaching the epitaxial growth layer 5.
2 or polycrystalline silicon 7 is buried, and the regions where elements are formed are insulated and separated from each other by the Si02 or polycrystalline silicon 7. 8 is Si02
The film 9 is an electrode wiring film aluminum layer.

Conventionally, there are the following examples of methods for selectively embedding metal or insulating material in the above-mentioned recesses.

Conventional example 1 (Figure 3) Substrate 1 of semiconductor or insulator, etc.
Using a resin pattern 12 formed of a negative-type photosensitive resin or a positive-type photosensitive resin on the substrate 1 as a mask, a recess 13 is formed using a liquid or gas that corrodes the substrate 11 such as a semiconductor or an insulator (FIG. b).

Next, S to be buried in the recess 13 provided in the substrate 11.
The i02 layer or the mold film 14 is formed by sputtering, spraying, etc. (FIG. c). In this state, the Si
The 02 layer or the metal layer 14 is deposited on the recesses provided in the substrate 11 and on the resin pattern 12. Next, when the resin pattern 12 is immersed in a solution that dissolves the resin pattern 12, the resin pattern 12 is removed and the resin pattern 12 is removed.
The upper Si02 layer or metal layer 14 is also removed, and the Si02 layer or metal layer 1 is formed only in the concave portion of the substrate 11, as shown in Figure d.
4 will be buried. Conventional example 2 (Fig. 4) A recess 22 is provided on a substrate 21 using a photoetching method (Fig. a),
A Si02 or metal layer 23 is deposited by vapor deposition, sputtering, or the like.

This state is shown in Figure b. Next, a photosensitive resin 24 is applied, and the layer 23 formed on the convex portion of the substrate 21 is exposed to a solution that corrodes the Si02 or metal layer 23 using the pinholes generated in the photosensitive resin 24. is removed, creating a cavity 25 (Figure d). In other words, the same state as shown in FIG. 3d can be formed. In such a conventional pattern forming method, for example, in Conventional Example 1, in order to deposit a metal or an insulating film directly onto the resin pattern, the process of forming the metal layer may be performed at a temperature higher than the temperature at which the resin pattern deteriorates. Otherwise, normal pattern formation cannot be performed.

Furthermore, when the insulating film is made of Si3N4, polycrystalline silicon, etc., the formation temperature of these films far exceeds 300°C.
The resin has already decomposed and pattern formation is no longer possible.
That is, since the insulating film and the metal film must be formed at a resin heat resistance temperature of about 300 qo or less, there are limitations to the insulating film and metal film that can be formed by this method, making it impractical. Furthermore, Conventional Example 2 is an improvement over Conventional Example 1, in that the photosensitive resin 24 is applied after the formation of the metal film or insulating film as shown in FIG. 4b. Although there are no restrictions on the formation conditions, the metal film or insulating film 23 is removed using pinholes in the photosensitive resin 24 formed on the convex portions of the substrate 21.

This caused the following problems. That is, the thickness of the waist 23 is significantly smaller than the width of the pattern to be removed, and the pinholes generated in the resin 24 described above tend to occur at the corners 26 in FIG. For this purpose, the film 23 is removed from the side, but if the pattern width is wide, as shown in FIG.
As shown in FIG. 5B, the film 23' remains at the center of the convex portion, and even if the resin 24 is removed, a normal pattern cannot be formed as shown in FIG. 5B. Also, if the membrane 23 is left immersed in the liquid for a long time, the sixth
As shown in FIG. 6A, part of the resin 24 is damaged and the film 23 is gradually removed, but as a result, the film 23 remains as shown in FIG. 6B, resulting in the formation of an incomplete pattern. The present invention completely eliminates such drawbacks and relates to a reliable pattern forming method.

Next, the configuration of the present invention will be described. The key point of the structure of the present invention is that a positive photosensitive resin is first coated, and then a layer made of a material that does not dissolve in the solvent of the positive photosensitive resin, such as a negative photosensitive resin, is applied to a layer that is significantly more than the positive photosensitive resin. Apply a thin layer, expose the entire surface of the substrate to light, then immerse it in a positive photosensitive resin developer or solution to completely remove unnecessary positive photosensitive resin, and then remove the surface of the insulating film or metal film to be removed. The goal is to fully expose the

Next, experimental data will be clearly explained in order to make the structure of the present invention easier to understand.

We have experimentally determined that a recess is formed on a semiconductor substrate and a photosensitive resin is applied to the recess.

In FIG. 7, a semiconductor substrate 31 has a concave portion 32 and a convex portion 33.
is formed, and when the photosensitive resin 34 is applied thereon, the film thickness is different between the relatively flat wide area 35 and the contact point between the recess 32 and the protrusion 33, that is, the apex 36 of the step. There is a significant difference in film thickness. This is because the flow of the resin layer 34 near the apex 36 becomes faster due to the step difference, and
It is presumed that it is formed thin because it is dragged toward the concave region or toward the convex region. FIG. 8 shows the film thickness at the apex 36 in FIG. 7 (minimum film thickness at the stepped part in FIG.
The figure shows the relationship with resin film thickness).

In the figure, data is shown for each step and the inclination angle of the step. According to the figure, for example, if the film thickness at a relatively flat area (35 in Fig. 7) is 0.8 mm, the film thickness at the apex 36 is less than half, 0.36 mm, and there are significant pinholes. film thickness.

The data in Figure 8 is for positive photosensitive resin AZ-135.
0J (company name: Situplay). Next, the configuration of the present invention will be explained. Figures 9a to 9e show an embodiment of the present invention.

A pattern is formed on a semiconductor substrate, an insulating substrate such as glass, ceramic, resin, etc., or a metal substrate 41 (hereinafter referred to as substrate 41) such as Cu, AI, etc. by photolithography, and convex portions 42 and concave portions 43 are formed in a predetermined shape. (Figure 9a)
.

In this case, it is desirable that the slope of the stepped portion be as steep as possible. Therefore, if the substrate 41 is etched by plasma etching or ion etching rather than chemical etching, an angle of 600 or more can be obtained. Next, an insulating film such as an Sj02 film, a Si3N4 film, or an AI203 film, a semiconductor film such as a polycrystalline silicon film, an epitaxially grown film, or a metal film 44 (hereinafter referred to as film 44) such as a polycrystalline silicon film or an epitaxially grown film is formed by a sputtering method or a vapor deposition method. (omitted)) (Fig. 9b).

The thickness of the film 44 may be just enough to bury the recess 43 provided in the substrate 41, but it depends on the subsequent steps involved in the present invention. In FIG. 9, the recess 43
The depth of the film 44 and the thickness of the film 44 are made the same. Next, a positive photosensitive resin 45, such as AZ-1350J (trade name), is applied to a thickness of 1 Am using a spinner, and heated at a moderate temperature of 60 qo to 90 qo so as not to cause thermal polymerization.
Heat treatment is performed for 0 to 3 minutes to dry the positive photosensitive resin 45, and then a negative photosensitive resin 46 such as KTFR (trade name) is applied on the positive photosensitive resin 45 to a thickness of 0.6 cm. It is coated and dried at 90°C for 10-30 minutes (Figure 9c).

In this state, if the thickness of the photosensitive resin at the top A of the convex portion is applied to FIG. 8, the thickness of the positive photosensitive resin 45 is 0.6, and the thickness of the negative photosensitive resin 46 is at least 0.14. The area next to the peak is extremely thin, and significant pinholes can be seen near this summit A. This is particularly noticeable in the negative photosensitive resin 46. The greater the number of pinholes near the top A, the greater the effect of the present invention. It is known that the film thickness at which the amount of pinholes increases in a negative photosensitive resin is generally about 0.6 mm. In order to make the film thickness near the vertex A 0.6〃, the average film thickness of the photosensitive resin layer is 1.0〃 from FIG. 8, so the negative photosensitive resin layer 46 in FIG. The film thickness is preferably 1.0 skin or less. Further, the minimum film thickness is practically 0.1 mm. If the film thickness is less than this, the controllability of the film thickness will be poor and the number of pinholes will be extremely large, making it unusable. That is, when the positive photosensitive resin is removed in the next step, the positive photosensitive resin layer 45 on the recessed portions is also removed due to the generation of pinholes, which is not practical. Therefore, it is desirable that the average film thickness of the negative photosensitive resin is 0.1 to 1.0 A in the flat area. On the other hand, the ratio of the thickness of the positive-working photosensitive resin to the negative-working photosensitive resin was experimentally found to be 10:1 to 1:1.

Next, in the state shown in FIG. 9c, the positive photosensitive resin is irradiated with light of a wavelength to which it is sensitive, in fact ultraviolet light emitted from a high-pressure mercury lamp.

In this state, the positive photosensitive resin 45 becomes easily soluble in a solvent. That is, positive photosensitive resin 45
By immersing the substrate in a special developer, diluted NaOH solution, or acetone solution, the positive photosensitive resin 45 on the convex portion of the substrate 41 is dissolved and removed by the solvent through the pinholes generated in the negative photosensitive resin 46. Then, the negative photosensitive resin 46 in this area also loses its adhesion and is easily removed. This state is shown in FIG. 9d. In the above process, the frequency of 10KHz to 500KH is immersed in a solvent.
Applying ultrasonic waves of about
The negative photosensitive resin on the convex portions can also be removed more completely.

If heat treatment is applied at 10 pC to 260 qC in the condition shown in Figure 9 d, the positive photosensitive resin 45 attached to the recesses will be removed.
The adhesion between the film 44 and the film 44 is improved, and a more complete pattern can be obtained in the next step without liquid seepage. As shown in FIG. 9D, the film 44 of the convex portion is completely exposed, so by immersing the film 44 in a liquid that corrodes or dissolves the film 44, the waist 44 of the convex portion is completely removed to the surface of the substrate 41. The resin layer is then removed by immersing it in a heated S04 solution or boiled acetone solution to obtain the state shown in FIG. 9e. In the process, the side surfaces of the positive photosensitive resin 45 in the concave portions are surrounded by the film 44, and the side surfaces of the positive photosensitive resin 45 in the convex portions are formed thin, and the negative photosensitive resin 46 has many pinholes especially near the apex. surrounded by
Therefore, the solution for dissolving the positive photosensitive resin 45 penetrates from the side surface of the positive photosensitive resin 45 in the convex portion of the negative photosensitive resin 46, which has many pinholes, and dissolves it.
On the other hand, the positive photosensitive resin 45 in the concave portion is surrounded by a film 44 on the sides and the negative photosensitive resin 46 on the top surface, but some parts are not covered with Oribe's negative photosensitive resin 46. Because the gap was extremely small, only a small amount of melting due to solution intrusion was observed. Rather, the rate of dissolution of the positive photosensitive resin 25 in the convex portions with exposed side surfaces is extremely fast. As described above, the above-mentioned embodiments of the present invention effectively utilize the ease of melting of the positive photosensitive resin and the remarkable ability to reduce the film thickness at the stepped portion of the negative photosensitive resin.
The purpose is to completely expose the film surface to be removed as shown in FIG. 9d.

In addition, the negative photosensitive resin on the concave part prevents pinholes in the positive photosensitive resin on the bottom surface, and also serves as a preventive film to prevent the resin in this area from being dissolved in the solvent in the step of FIG. 9d. . Next, regarding other configuration examples, Fig. 10 a to g
Explain using.

Step of providing convex portions 42 and concave portions 43 on substrate 41 (first
0a), the step of providing the film 44 (FIG. 10b), and the step of applying the positive-type photosensitive resin 45 and the negative-type photosensitive resin 46 (FIG. 10c) are the same as the above-mentioned configuration example. Omitted.

Next, if the entire surface is irradiated with ultraviolet light in the state shown in FIG. It becomes ashes little by little.

In particular, since the film thickness is the thinnest near the top A of the convex portion, the negative-type photosensitive resin is removed as shown in FIG. 9d, and this significantly helps the dissolution of the positive-type photosensitive resin in the next step. (10th
Figure d). Next, by immersing it in a solution that dissolves the positive photosensitive resin, such as a special developer, acetosol, or diluted Na○goya, the positive photosensitive resin on the convex portions can be easily removed, and at the same time, the negative photosensitive resin can also be removed. (Figure 10e)
). The membrane 44 to be removed is completely exposed. As mentioned above, this process becomes more reliable if ultrasonic vibration is applied in this process as in the above configuration example. 1000 before immersing the membrane 44 in a liquid that corrodes or dissolves it.
Heat treatment at a temperature of 0 to 260 oo increases the adhesion between the film 44 in the recess and the positive photosensitive resin 45, and further improves acid resistance. FIG. 10f shows a process in which the film 44 is completely removed, and FIG. 10g shows the photosensitive resin layers 45 and 46.
This figure shows the state in which the process of the present invention has been completed by completely removing . The film thickness ratio of the positive-type photosensitive resin and the negative-type photosensitive resin in this configuration example is the same as in the above-mentioned configuration example.
:1 to 1:1 is desirable.

The state shown in FIG. 9e or 10g can be used as a step in a planarization process such as isolation between elements or BI. Further, in the configuration example of the present invention, the resin on the upper part of the substrate 41 was described as a negative photosensitive resin (No. 9
46 in Figure 10), but is not limited to this,
Resins such as ferrite rubber, PVA, polyimide, wax, etc. may also be used, and the effects of the present invention will be the same.

That is, any material may be used as long as it does not dissolve in the solvent of the positive photosensitive resin. Next, the effects of the present invention will be described.

(2) As described above, in the present invention, the surface of the film 44 to be removed can be completely exposed and immersed in the solution of the film 44, so that the film 44 to be removed can be completely removed and the desired pattern can be formed. can.

(2) Furthermore, since photosensitive resin films with different properties are coated twice on the surface that should not be removed, defects such as pinholes on this surface can be significantly reduced.

(2) In addition, in the present invention, since the positive photosensitive resin that easily melts when exposed to light is provided on the film 44 to be removed, it is difficult to remove the film 44 as shown in FIGS. 5 and 6 described in the conventional example. There are no defects due to leftovers, etc., and the pattern forming process is easy.

[Brief explanation of the drawing]

Figures 1 a to c are explanatory diagrams of the principle of the pattern forming method;
The figures are diagrams showing application examples of the present invention, Figures 3 a to d, and Figure 4 a.
- d are process diagrams of the conventional example, FIGS. 5 a, b, and 6 a, b are diagrams for explaining the drawbacks of the conventional example, and FIGS. 7 and 8 are diagrams for explaining the present invention. , Figures 9a-e, Figures 10a-
g is a process chart for explaining one embodiment of the present invention. 41...Substrate, 44...Membrane, 45...
...Positive photosensitive resin, 46...Negative photosensitive resin. Figure 1 Figure 2 Figure 3 Figure 4 Figure 7 Figure 5 Figure 6 Figure 8 Figure 9 Figure 10

Claims (1)

[Scope of Claims] 1. A step of attaching a metal or insulating layer along the front surface of the substrate having an uneven surface in substantially the same shape as the uneven surface, and depositing a positive die on the metal or insulating layer. a step of applying a photosensitive resin, and applying a negative photosensitive resin that is sensitive to the same wavelength as the positive photosensitive resin and does not dissolve in the solvent of the positive photosensitive resin on the positive photosensitive resin; Forming the negative photosensitive resin thinner on the side surface of the positive photosensitive resin, forming pinholes in the negative photosensitive resin on the side surface, and simultaneously forming the negative photosensitive resin on the positive photosensitive resin. a step of exposing the negative photosensitive resin to light of the same wavelength; and a step of removing the positive photosensitive resin on the convex portions of the uneven surface through the pinhole using a liquid that dissolves the positive photosensitive resin. A pattern forming method comprising the steps of: removing the metal or insulating layer on the convex portions of the uneven surface using a liquid that corrodes the metal or insulating layer. 2. Claim 1, characterized in that in the process of removing the positive photosensitive resin on the convex portions of the uneven surface with a liquid that dissolves the positive photosensitive resin, the positive photosensitive resin is dissolved while applying ultrasonic vibrations.
The pattern forming method described in section. 3 After removing the positive photosensitive resin on the convex portions of the uneven surface with a liquid that dissolves the positive photosensitive resin, the substrate was
Claim 1 characterized in that the heat treatment is performed at 0°C.
The pattern forming method described in section. 4. A patent claim characterized in that, at the time of the exposure step, a step of removing part or all of the layer made of a material that does not dissolve in a solvent of the positive photosensitive resin on the convex portions of the uneven surface in a plasma atmosphere is also used. The pattern forming method according to item 1. 5. Claim 4, characterized in that the plasma atmosphere consists of O_2 or a mixed gas of O_2 and N_2.
The pattern forming method described in section.