JPH04278536A - Manufacture of semiconductor element - Google Patents

Abstract

PURPOSE:To obtain the manufacturing method of a semiconductor element capable of surely eliminating evaporation material of unnecessary parts by lift-off. CONSTITUTION:In the manufacturing method of a semiconductor element wherein a desired evaporation pattern is formed by a lift-off method using photo resist, the whole surface of a substrate 14 is coated with photo resist, and a resist pattern 28 is formed on the substrate by selective exposure and development. After desired evaporation material 30 is evaporated on the whole surface of the substrate and the whole surface is irradiated with ultraviolet rays, the resist pattern 28 is baked. After that, the resist pattern 28 is eliminated by lift-off, together with the evaporation material 30 on the resist pattern 28.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing semiconductor devices using a lift-off method. The lift-off method is a method often used for forming electrodes of semiconductor devices, and after exposing and developing a positive resist in advance so as to leave the resist in areas where no deposits are desired, the resist is deposited over the entire surface. Thereafter, the resist is dissolved with an organic solvent to remove the deposited material on the resist, thereby forming a desired pattern of the deposited material.

In this type of lift-off method, compound semiconductor crystals are pasted on a substrate in a comb-teeth pattern, and when manufacturing a multi-element infrared sensing element in which signals are extracted from each compound semiconductor crystal part, a desired signal is selectively applied. It is often used as a method for depositing vapor deposits.

0003

[Prior Art] To form a desired vapor deposition pattern using a positive resist by the lift-off method, first apply the positive resist to the entire surface of the substrate, and then apply the resist to the areas where you do not want to leave the vapor deposits. The exposed portions of the resist are removed by patterning exposure and development.

[0004] Next, a desired vapor deposition is performed on the entire surface, and when the resist is immersed in an organic solvent, the organic solvent dissolves the resist into the solvent, and the deposited material on the resist is removed to form a desired pattern of the deposited material.

[0005]

[Problem to be Solved by the Invention] However, when forming a desired vapor deposition pattern by the lift-off method, if the vapor deposited material has good step coverage, the vapor deposited material may be connected to the sides of the resist without being cut. However, there was a problem in that lift-off was extremely difficult and a defective vapor deposition pattern occurred.

Furthermore, when a positive resist is subjected to baking, exposure, and development, its shape becomes dull at the edges, and when a deposit is deposited on the entire surface, the deposit is connected without being cut at the edges of the positive resist. , lift-off may be difficult. In particular, this tendency becomes stronger as the thickness of the deposit increases.

The present invention has been made in view of the above points, and an object thereof is to provide a method for manufacturing a semiconductor device that can reliably remove deposits from unnecessary portions by lift-off. .

[0008]

[Means for Solving the Problems] In a method for manufacturing a semiconductor device in which a desired vapor deposition pattern is formed by a lift-off method using a positive resist, the positive resist is applied to the entire surface of the substrate, and then the substrate is coated by selective exposure and development. After forming a resist pattern, a desired deposition material is deposited over the entire surface of the substrate. Next, after the entire surface is exposed to ultraviolet rays, the resist pattern is baked, and then the resist pattern is removed together with the deposited material thereon by lift-off.

[0009] Alternatively, a full exposure step to ultraviolet light may be performed before the step of depositing the vapor deposit.

0010

[Action] By irradiating the positive resist with ultraviolet rays,
The polymerization of the positive resist is cut. When a positive resist that has been polymerized in this way is baked at a predetermined temperature, gas is generated from the positive resist and cracks appear in the deposited material on the resist, making lift-off using an organic solvent very easy. Can be done.

[0011]

EXAMPLES An example in which the manufacturing method of the present invention is applied to a multi-element type infrared sensing element will be described below.

FIG. 1 shows a schematic perspective view of a multi-element type infrared sensing element 10, in which HgC is formed on a sapphire substrate 12.
A compound semiconductor crystal 14 such as dTe is bonded with an adhesive in a comb-like shape.

A light receiving portion 16 for receiving infrared rays is defined in each compound semiconductor crystal 14 formed in a convex shape by a pair of light shielding films 18 , and an antireflection film 20 is defined by a pair of light shielding films 18 .
The light receiving section 16 is formed so as to extend through the bottom of the light receiving section 16 . The light shielding film 18 is made of aluminum or the like, and the antireflection film 20 is made of ZnS or the like.

[0014] At one end of each compound semiconductor crystal 14, an individual electrode 22 for extracting a signal is provided by wire bonding, and at the other end, a common ground electrode 24 is provided to be connected to ground.

In manufacturing the multi-element infrared sensing element 10 having such a structure, an electrode, an antireflection film, or a light shielding film is formed on each convex compound semiconductor crystal 14 by the lift-off method described below. .

An example in which the manufacturing process of the present invention is applied to manufacturing an infrared sensing element will be described with reference to FIG.

After applying a positive resist to the entire surface of the compound semiconductor crystal 14 such as HgCdTe, baking is performed at 70 to 80° C. for about 10 minutes. Next, the positive resist is selectively exposed using a mask and developed, resulting in the image shown in Figure 2 (
As shown in a), a resist pattern 28 is formed on the compound semiconductor crystal 14.

Next, as shown in FIG. 2(b), a deposit 30 is uniformly deposited over the entire surface. The deposit 30 is a substance that transmits ultraviolet rays, and for example, an insulating material such as ZnS or SiO2 or very thin Ni or Cr is used.

Next, as shown in FIG. 2(c), the entire surface is exposed to ultraviolet light. As a result, the ultraviolet rays pass through the deposit 30 and cut the polymerization of the positive resist 28.

[0020]Positive resist 2 whose polymerization has been cut in this way
When resist 28 is baked at 70 to 80° C. for about 10 minutes, bubbles 32 are generated in resist 28 as shown in FIG. 2(d). The resist 28 expands due to the bubbles 32, and cracks 31 appear in the deposit 30 on the resist 28.

Next, as shown in FIG. 2(e), when immersed in a stripping solution such as acetone, the stripping solution can easily penetrate into the resist 28 through the cracks 31, and as a result, the resist is immersed in the deposited material thereon. Figure 2
A vapor deposition pattern 30 as shown in (f) can be obtained.

In the above embodiment, the ultraviolet exposure step is performed after the vapor deposition in step (b), but steps (b) and (c) are reversed, and the vapor deposition step is performed after the ultraviolet exposure. You can do it as well.

Furthermore, the present invention can be used not only when forming a vapor deposition pattern on a compound semiconductor crystal, but also when forming a vapor deposition pattern on a sapphire or silicon substrate.

In particular, when the substrate is transparent to ultraviolet rays, the entire surface of the substrate can be exposed to ultraviolet rays from the back side.
In this case, a substance that does not transmit ultraviolet rays can also be used as the deposit.

[0025]

Since the present invention is constructed as described in detail above, it is possible to reliably remove deposits from unnecessary portions by lift-off.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of an infrared sensing element.

FIG. 2 is a diagram showing a manufacturing process of an example of the present invention.

[Explanation of symbols]

10 Multi-element infrared sensing element 12 Sapphire substrate 14 Compound semiconductor crystal 16 Light receiving part 22 Individual electrode 24 Common electrode 28 Positive resist 30 Vapor deposits 31 Crack 32 Bubbles

Claims (3)

[Claims] 1. A method for manufacturing a semiconductor device in which a desired vapor deposition pattern is formed by a lift-off method using a positive resist, in which a positive resist is applied to the entire surface of a substrate (14), and then the resist is deposited on the substrate by selective exposure and development. After forming a pattern (28) and depositing a desired vapor deposit (30) on the entire surface of the substrate and exposing the entire surface to ultraviolet rays, the resist pattern (28) is baked, and then the resist pattern (28) is A method for manufacturing a semiconductor device, characterized in that it is removed together with the upper deposit (30) by lift-off. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the step of exposing the entire surface to ultraviolet rays is performed before the step of depositing the vapor deposit (30). 3. The method of manufacturing a semiconductor device according to claim 1, wherein the substrate (14) is an ultraviolet-transmissive substrate, and the entire surface of the substrate is exposed to the ultraviolet rays from the back side of the substrate.