JPS6115331A - Method of hardening thermally deformable material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for controlling the shape of thermally deformable materials, such as resists, that are exposed to high processing temperatures during the manufacture of semiconductor devices.

[Summary of disclosure]

The present invention relates to a method for controlling the shape of thermally deformable materials such as resists that are exposed to high processing temperatures during the manufacture of semiconductor devices, such as when a pattern of resist is later exposed to higher temperatures. using a mold or support material that surrounds said resist patterns so as to maintain their shape when exposed, and a mold or support material of a resist that is different from said resist pattern and, e.g., a resist of said resist pattern; For example, heat to a temperature of about 200° C. for 30 minutes. Resist patterns cured in this manner can be further exposed to processing steps involving heating up to 750°C without significant changes in the lateral dimensions of the resist patterns (Polyimide, spin encapsulation, etc.). Other mold or support materials may also be used, such as hardened glass, and deposited aluminum.

[Prior art]

Ion implantation, reactive ion etching, and ion implantation.
Today's Vs require strict temperature conditions for milling.
In LSI technology, resist curing is an extremely important process. In those methods, the semiconductor wafer used is exposed to a temperature exceeding the glass transition temperature of the resist material, resulting in a resist film formed on the wafer.
The pattern may be distorted. As a result, the resist
Large variations in pattern width occur. A typical solution to this problem is to harden the resist by cross-linking so that it can withstand higher processing temperatures. For example, when using the well-known diazo-sensitized novolak resist system, the developed resist pattern begins to deform at 120°C, whereas the resist cured by cross-linking is much more sensitive than 200°C. Can withstand processing temperatures exceeding . IEDMT
An example of such a cross-linking method is given in 1980, 1980, in ``Chemical Digest,'' pages 574-575.

Typical resist curing techniques include exposing the resist to Bakele, plasma, ion or electron implantation, or deep ultraviolet radiation in the 200 to 3'00 nm spectral region at elevated temperatures before processing the resist. However, the baking method remelts the resist and produces deformations in the resist profile similar to those caused by subsequent high temperature processing. Plasma, ion implantation, and ultraviolet light methods tend to produce hardened films on the resist surface unless the implant dose or energy used is extremely high to penetrate the entire thickness of the resist.

In that case, the bulk of the resist material typically remains soft and is susceptible to deformation due to subsequent high temperature processing. Typically, the patterns on wafers processed with the above-mentioned techniques that produce a hardened film will remain intact after processing if they are fine patterns, but will have a greater softness, center area, or If the pattern is large, it will wrinkle and become rough. On the other hand, electron beam curing does not have the disadvantages of the technology, which produces a hardened film due to good electron penetration. Cause damage. Similarly, ion bombardment can also cause wafer damage if the ion energy is increased so that a hardened film does not occur. Furthermore, excluding the direct baking method (,
All the methods mentioned above depend on the incident energy, injection volume, time,
It depends on the manipulation of several process parameters such as power, gas type, flow rate, pressure, and temperature.

[Problem that the invention seeks to solve]

It is an object of the present invention to provide a surface-conformable material such that the cross-section of a thermally deformable material, such as a developed resist pattern, does not undergo significant deformation when exposed to high temperatures up to 750°C during the manufacture of semiconductor devices. Using the mold material and support material,
2) To provide a method for controlling the cross section of a material. The method of the invention is simple, inexpensive and compatible with conventional technology.

[Means for solving problems]

The present invention involves forming a thermally deformable material having a given structure on the surface of a substrate, surrounding the exposed surface of the material with a support feature, and removing the support feature as described in -. The material and the support material are cured using sufficient time and temperature to cure the material so that the material maintains its given structure when the material is further heated. Provided is a method of curing a thermally deformable material upon heating.

In one embodiment, the method of the present invention includes applying a developed resist to a mold comprising a resist different from the resist described above, a material selected from the group consisting of polyimide, spin-coated glass, and evaporated aluminum. The structure of the developed resist is maintained by surrounding it with a support material and baking using a time and temperature that sufficiently cures the developed resist over its entire cross section. The above developed resist is, for example, Sh
It is a novolac type resist such as AJ135DJ (trade name) manufactured by IPLAY.

The mold material or supporting phase surrounding the developed resist is
Another resist is, for example, polymethyl methacrylate (PMMA) cast in chlorobenzene. After forming a support or mold material around the developed resist pattern, the wafer is introduced into a furnace, flushed with nitrogen, and heated for 60 minutes at a temperature of 2 oo'C. The wafer is removed from the furnace and the PMMA is stripped by immersing it in an ultrasonically agitated acetone bath for 6 minutes.

The remaining developed resist patterns can be exposed to temperatures up to 750°C without significant changes in their cross-sectional dimensions. AZ1350, AZ1450SAZ24
0'D, Hunt204, Hunt206, Kodak
809, KTFR, KORl and) (jtachi
Novolac type resists such as MR8 (product name),
It can be cured using the method of the invention. In addition to the above-mentioned resist, PMMA may be used as a mold material, that is, a support material.
Copolymers or terpolymers based on polyimide,
Spin coated glass or vapor deposited aluminum may also be used. All PMMA-based materials do not deform when coated onto a resist pattern and are baked at high temperatures, and can be removed with solvents even after being baked at high temperatures. Alternatively, both resists may be exposed to deep UV light to increase the solubility of the mold material or support material. If spin-coated glass is used, the glass can be stripped using buffered hydrofluoric acid. If vapor deposited aluminum is used, the aluminum can be stripped using a mixture of nitric and phosphoric acids. The above system is compatible with the prior art, and the resulting resist patterns do not wrinkle, crack, or peel, as occurs with all conventional curing techniques, especially in large patterns.

〔Example〕

FIG. 2 shows a semiconductor substrate 1, preferably made of silicon or other semiconductor material such as germanium or gallium arsenide. If desired, a layer (not shown) of an adhesion promoter, such as hexamethyldisilazane (HMDS), is spin-coated to a thickness of approximately 200 holes over the surface of the substrate 10 in a known manner.

FIG. 2 also shows a resist pattern 2 disposed on the substrate 1. FIG. To form the resist pattern 2, first a novolac type resist such as AJ1350J is spin-coated onto the substrate 1.

The resist spin-coated substrate 1 is subjected to a pre-baking process at a temperature of 85° C. for approximately 50 minutes. The substrate 1 is removed from the furnace and the resist is exposed through a mask with a mercury lamp providing broad spectrum radiation. Next, AJ13
The above resist is developed using a 50 J developer by a well-known method to form a developed resist pattern 2. Instead of a mercury vapor lamp, other radiations such as electron beams, ultraviolet radiation, or X-rays can also be used. In the structure shown in FIG. 2, the resist pattern 2 has a thickness of approximately 0 to 5 μm, for example.
, but can have any height that can be conveniently formed.

FIG. 1 shows the structure of FIG. 2 in which the developed resist butter 72 is surrounded by mold or support material. After forming the resist pattern 2, if desired, a layer of adhesion promoter (not shown) such as HMDS is spin coated onto the exposed surface of the substrate 1 and onto the surface of the developed resist pattern 2. You may.

Next, a PMMAO layer 6 having a molecular weight of 496°00 is deposited on the substrate 1 at a thickness of 27 to 30 μm so that a mold or support surrounding the developed resist pattern 2 is formed.
Spin coat to a thickness in the range m. -P other than the above molecular weight
I can use MMA. Layer 6 should have a height that exceeds the height of the elements on the substrate.

After forming layer 3, a standard furnace for processing semiconductor wafers is cleaned with nitrogen and the substrate 1 is introduced into said furnace and heated for 160-250 min in a non-oxidizing or oxidizing atmosphere.
at a temperature in the range of °C for a time in the range of 60 to 15 minutes.
Heat. Preferably, a non-oxidizing atmosphere such as argon, nitrogen or forming gas is used. In one embodiment, the substrate 1 is heated at a temperature of 200° C. for 60 minutes.

After the heating step, the substrate 1 is removed from the furnace and immersed in an acetone bath with ultrasonic stirring for 6 minutes to peel off the layer 5.

Then, the substrate 1 with the developed resist pattern 2 is subjected to a normal semiconductor wafer processing step to form a 750°
Even when exposed to temperatures up to C, the resist pattern 2 does not undergo significant deformation. The change in lateral dimension in resist pattern 2 processed according to the method of the invention and then baked at 750° C. is less than 805 μm. Although control of the lateral dimensions of the developed resist pattern 2 is most important, the longitudinal shrinkage after baking at 500° C. was between 20 and 60%. This vertical shrinkage is
It is acceptable and does not compromise any necessary semiconductor processing steps.

In the above treatment, AJ135, a novolac type resist, was used.
0. f was used, but AZ1350, AZ1450, AZ
2400.1 (unt204, Hunt206, Kod
ak 809, KTFR, KOR, and Hitachi
Other resists such as MR8 can also be cured by the method of the present invention. As the mold material, that is, the supporting material, P
In addition to MMA, a PMMA'i-based copolymer or terpolymer, or polyimide may be used. Also, as previously mentioned, rotary glass, which can be stripped with buffered hydrofluoric acid, and vapor-deposited aluminum, which can be stripped with a mixture of nitric and phosphoric acids, can also be used as mold materials or supports. It can be used as a material. These mold or support materials can be coated onto the resist pattern without deforming it and can be removed with a solvent even after baking at high temperatures.

〔Effect of the invention〕

By using the method of the present invention, the cross section of a thermally deformable material such as a developed resist pattern during the manufacture of semiconductor devices can be prevented from being significantly deformed even when exposed to high temperatures of up to 750°C. is controlled using a mold material or support material that conforms to the surface.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a semiconductor substrate with a developed resist pattern surrounded by a mold or support material conforming to the surface; FIG. 2 is a cross-sectional view of a semiconductor substrate with a developed resist pattern on its surface; FIG. DESCRIPTION OF SYMBOLS 1... Semiconductor substrate, 2... Developed resist pattern, 6... Polymethyl methacrylate (PM
MA) layer (mold material or support material). 1-・9. Semiconductor A Book 1 Board 2...-Current L&S #L1; Regis 1-1 G Turn 3.
-Supporting material (PMMA layer) Fig. 1 Cross-sectional view of the semiconductor semiconductor substrate Fig. 2

Claims (2)

[Claims] (1) Forming a thermally deformable material having a given structure on the surface of a substrate, surrounding the exposed surface of the material with a support material, and using sufficient time and temperature to cure the material. and heating the material and the support material. Method of curing thermally deformable materials. (2) Claims in which the thermally deformable material is a resist and the support material is a material selected from the group consisting of a resist different from the resist, polyimide, spin-coated glass, and vapor deposited aluminum. The method described in paragraph (1).