JPS60247922A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To introduce impurities deep in a substrate at manufacture of a semiconductor device by a method wherein light sensitive resin having high heat resistance is used as the mask material of a mask. CONSTITUTION:An impurity introducing mask 10 is formed on the main surface of a semiconductor substrate 1, and by introducing impurities into the substrate 1 through the window opened part of the mask 10, an impurity introduced region is formed in the necessary range. At this time, light sensitive resin having high heat resistance is used as the mask material of the mask 10. Impurities are introduced deep in the substrate 1 through the window opened part obtained according to selective exposure and development treatment to the mask material thereof. Accordingly, implantation of impurity ions according to a large current can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a technique for selectively introducing impurities into a semiconductor.

[Background technology]

A semiconductor processed using photoresist (photosensitive corrosion-resistant resin) or photoresist as an impurity introduction mask material when impurity ions are introduced from the surface into a part of the semiconductor substrate in the manufacturing process of semiconductor integrated circuit devices (IC, LSI). It is generally known that oxides (S+02) and the like are used.

The main component of the photoresist in this case is, for example, polyvinyl cinnamate, which is a type of polymer compound, and this takes advantage of the fact that polymerization progresses under ultraviolet rays and becomes insoluble in organic solvents such as trichlene. However, such photoresists have low heat resistance (approximately 200°C), and in order to obtain a deep diffusion layer, impurities are introduced by ion implantation using a high voltage (for example, applying a high voltage of 1×10'V or more) and a large current. It thermally decomposes, making it useless as a mask material, and it is difficult to implant high-concentration, high-energy ions into photoresist.

For example, when forming a deep n-type diffusion region for taking out the collector from the n-type buried layer 2 at the bottom of a bipolar npn transistor formed on the silicon substrate shown in FIG. Phase chemical deposition (CVD)
A thick silicon oxide (Sing) or phosphosilicate glass (referred to as PSG) is formed by a method such as a method. Using this as a mask material 3, high concentration impurity ions are shallowly implanted into the substrate 1 through the window opening 4 to obtain a filler deposit 45.

Next, a deep diffusion layer 6 was obtained by heat treatment over a long period of time.

However, this method of introducing impurities requires an extra step of preparing a photoresist etching mask (indicated by dotted line 7) to open window openings 4 in the mask material 3, and photo-etching the mask material 3 through this. be. or,
In order to obtain a deep diffusion layer, the heat treatment time becomes longer, and the diffusion region expands in the lateral direction accordingly. Furthermore, it is necessary to provide a margin in the design for the space expanded in the lateral direction of the diffusion region, and as a result, it has been found that there is a limit to the integration of the IC.

The present inventor has developed a photosensitive polymer composition (photosensitive polyimide) mainly consisting of polyamic acid in place of the above-mentioned ordinary photoresist (Oko Materials, July 1983 issue, pp. 30-34).
We focused on utilizing its buttering properties and high heat resistance in impurity-introducing masks.

[Purpose of the invention]

One object of the present invention is to provide a method for forming a diffusion region in a semiconductor that enables impurity ion implantation using a large current.

Still another object is to provide a method for manufacturing a semiconductor device that can reduce the number of steps and provide a highly accurate diffusion pattern.

Still another object is to provide a method for manufacturing a semiconductor device that can be easily fabricated in a high stacking scale.

The above and other objects and novel features of the present invention will become clear from the description of this specification and the accompanying drawings. A brief explanation is as follows.

That is, when an impurity introduction mask is formed on the main surface of a semiconductor substrate and an impurity is introduced into the semiconductor through the window opening of the mask to form an impurity introduction region in a required range, the mask material of the mask has high heat resistance. Impurities are introduced deeply into the substrate using a photosensitive resin, such as a photosensitive polyimide, and this photosensitive polyimide is used, for example, as a polyamic acid φ bisacide photocrosslinking agent, an amine compound having a carbon-carbon double bond, etc. , is a photosensitive polymer composition consisting of a compound that contains one or more hydroxyl groups in the molecule and has a boiling point of 150°C or higher at normal pressure, and because the photosensitive polyimide has high heat resistance, it can be This achieves the above object by making impurity ion implantation possible.

[Example 1] In the following examples, photosensitive polyimide is mainly used as the photosensitive resin having high heat resistance, but the invention is not limited thereto.

FIG. 2 to FIG. 6 show an embodiment of the present invention, in which the semiconductor layer is formed deep inside the semiconductor from the surface of the n+ type scattering layer 12 connected to the n+ type buried layer 2 embedded in the silicon substrate IK. (1) Second process, which will be explained below with reference to drawings of each process
As shown in the figure, silicon doped with n- type impurities is epitaxially grown on the n++ buried layer 2 to form an n- type silicon layer (silicon base) 1 with a thickness of 1.7 μm. A silicon oxide (SIO) film 8 is formed by thermal oxidation on the surface of this n-type silicon substrate 10 to a thickness of about 90 OA, and a silicon nitride (Si, N4) film is formed on it by CVD (vapor phase chemical deposition). 9 to a thickness of 140 OA.This is followed by a normal photoetch process (for example, CF
, +4%0. plasma etch) K, 840, film 8,
Parts of Si, N, and fi9 are selectively etched to form window openings.

(2) After this, a photosensitive polyimide solution (30 poise, resin concentration 14% by weight), which is the mask material of the impurity introduction mask, was used.
) was applied using a spinner, and a pulley bake was performed at 80° C. for 30 minutes to form a photosensitive polyimide film 10. Next, the photosensitive polyimide film 10 in areas other than the window openings is selectively exposed using an ordinary ultraviolet aligner. The appropriate exposure energy at this time is 50 to 100 mJ. Then normal (
Developed for 5 minutes in a developer of Nl-Mefk-2-pyrrolidone/water = 4/IC@volume ratio), and rinsed with the water removed. Subsequently, heat treatment is performed at 200° C. for 30 minutes and at 400° C. for 60 minutes to form a polyamic acid pattern as shown in FIG.

(3) Next, using an ion implantation device (not shown), phosphorus (P) ions are implanted into the substrate 1 as shown in FIG.
d. Implantation is performed at an ion acceleration voltage of, for example, 160 KV. At this stage, a pre-deposition (abbreviated as pre-deposition) #11 is formed at a depth of 1 μm from the surface in the n-type silicon substrate 1 on which the polyimide film 10 is not formed.

(4) After this, dry etching is performed using an oxygen plasma asher apparatus to remove the polyimide film on the surface as shown in FIG.

(5) Finally, heat treatment is performed at 1000° C. for 30 minutes in an oxygen atmosphere to stretch the pre-devo layer 11 by diffusion until it connects with the buried layer 2, thereby obtaining an n+ type scattered layer 12 which will become an impurity-introduced region. At this time, since the heat treatment is performed in an oxygen atmosphere, an oxide (Sin film 13) is simultaneously formed on the surface.

The photosensitive polyimide used in the present invention has photosensitivity like conventional photoresists, and after subsequent heat treatment, it becomes a polyimide group that has high heat resistance (approximately 430°C) similar to conventional polyimide resins. It includes everything.

Among such photosensitive polyimides, there is particularly a photosensitive polymer composition developed by the present inventors, which is coated with the following (2) [F]).

That is, (5) consisting of a polyamic acid, a bisazide photocrosslinking agent, an amine compound having a carbon-carbon double bond, and a compound that contains one or more hydroxyl groups in the molecule and whose boiling point is 150 ° C. or higher at normal pressure. A photosensitive polymer composition using a polyamic acid whose structure is represented by a repeating unit of general formula (1).

(However, R1 represents a divalent aromatic ring-containing organic group or a silicon-containing organic group) Represents a droxyalkyl group, an alkoxy group, an alkyl ester group, or an amino group, and the N group is in the meta or bara position in the benzene nucleus. A bisazide photocrosslinking agent represented by the formula (1) is used, and the compounding ratio is 2 to 10 parts by weight per 100 parts by weight of the polyamic acid represented by the general formula (1). Polymer composition.

By applying such a photosensitive polymer composition (F) to the above-mentioned examples, the effect can be best exhibited.

〔effect〕

According to the present invention described in Example 1, the following effects can be obtained by taking advantage of the mechanical properties of photosensitive polyimide.

(1) Photosensitive polyimide used as a mask for impurity ion implantation has heat resistance and mechanical properties equivalent to or higher than polyimide resins currently used in LSIs, etc., so it can be used with high energy and large current. Damage to the mask can be prevented even when ion implantation is performed, and impurities can be introduced into the semiconductor layer at a high concentration and deep.

(2) Since impurities can be introduced deep into the semiconductor layer, lateral spread can be reduced even when forming a deep diffusion layer. In Example 1, for example, the diffusion spread in the case of shallow ion implantation was 1.4μ.
In contrast, in the case of deep ion implantation according to the present invention, the diffusion spread is only about 0.6 μm. This makes it possible to highly integrate and refine semiconductor devices.

(3) By directly using photosensitive polyimide as a mask for impurity ion implantation, the usual photoresist process is omitted, reducing the number of processes and making it possible to cut costs.

(4) Photosensitive polyimide has a sensitivity equal to or higher than that of high-sensitivity rubber-based photoresists for LSI, and also has excellent resolution, making it possible to process fine diffusion patterns.

(5) By using a directly photosensitive polyimide film, 1
Since patterning can be performed in multiple etching steps, processing accuracy can be improved compared to a method in which a polyimide film is formed and patterned by photo-etching.

[Embodiment 2] FIGS. 7 to 15 show another embodiment of the present invention, in which np as part of an IC (semiconductor integrated circuit) σ)
n) It is a process sectional view of the manufacturing process of a transistor.

(1) As shown in FIG. 7, a p-type silicon crystal substrate 14
The n- type silicon I@1 is epitaxially grown by burying the n+ type buried layer 2 and the p type buried layer 15 thereon.

(2) As shown in FIG. 8, an oxide film (SiO□ film) 15 is placed on the surface of the n-type silicon layer 10 using an impurity introduction mask.
By ion-implanting (boron) and further thermal diffusion, an isolation p-type layer 17 is formed so as to be connected to the p+-type buried layer 15.

(3) N-type silicon layer] The oxide film 15 on the surface is removed by etching, and as shown in FIG. 9, an oxide film 8 by thermal oxidation and a nitride film 9 by CVD are newly formed.

(4) As shown in FIG. 10, using the photoresist 18 as a mask, a part of the oxide film 8 and nitride film 9 (the part to be the collector extraction part) 4 is etched to open a window.

(5) A photosensitive polyimide solution serving as a mask material for an impurity introduction mask is coated on the entire surface with a spinner, and prebaked to form a photosensitive polyimide film 10.

Next, a portion of the film is selectively exposed to light using an ultraviolet aligner, and a high heat treatment is performed to form a photosensitive polyimide film 10 such that the window opening 4 is exposed as shown in Figure 11. After that, baking is performed to form a polyimide film.

(6) Using an ion implantation device using the above polyimide film as an impurity introduction mask, P (
IJ) ions are implanted into the nlJl layer 1 to form a predevo layer 11 deep from the surface of the substrate 1, as shown in FIG.

(7) After removing the polyimide group by dry etching, heat treatment is performed in an oxygen atmosphere to thermally diffuse the green deposit layer 11 and introduce impurities so as to connect it to the n+ type buried layer 2 as shown in FIG. Extract the collector that becomes the area 'Ln
A + type diffusion layer 12 is formed.

(8) The surface oxide film 19 is formed thickly, a part of it is opened by normal photoetching, and B (poron) ions are implanted and thermally diffused to form a base p as shown in FIG.
fm region 20 is formed.

(9) A part of the oxide film is photoetched, As (arsenic) ions are implanted, and thermally diffused to form an emitter n+ type region 21 as shown in FIG. At the same time as this emitter diffusion, As is also applied to the surface of the collector extraction part.
It can be diffused and have low anti-inflammatory properties.

〔effect〕

According to the present invention described in the second embodiment, the same effect as in the case of the undercurrent side 1 can be obtained, and a miniaturized IC can be obtained.
can be provided.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, in an IC, if photosensitive polyimide is used as a selective diffusion mask for an isolation region using p-type diffusion to electrically isolate between elements, the lateral expansion of the isolation diffusion layer can be reduced and the The ration area can be significantly reduced. This makes it possible to provide a highly integrated IC.

[Application field]

The present invention can be applied to all semiconductor devices (IC, LSI) including an impurity ion implantation process using a large current.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a semiconductor device showing an example of impurity ion implantation and diffusion using an oxide film mask. FIGS. 2 to 6 show an embodiment of the present invention, and are cross-sectional views of process steps for implanting and diffusing θ) impurity ions into the surface of a semiconductor substrate. FIGS. 7 to 15 show another embodiment of the present invention, and are process sectional views of a diffusion process for forming a semiconductor substrate npn) transistor. 1... Semiconductor base (n- type silicon), 2... n+
+buried layer, 3...CVD semiconductor oxide (Sing) film, 4...window opening, 5...bride layer, 6...n+
Mold diffusion l, 7... Photoresist mask, 8... Thermal oxide film, 9... Nitride film, ]0... Photosensitive polyimide film, Goto... Pre-deposition layer, 12... n+ type number 13...thermal oxide film, 14...p-
type silicon substrate, 15...p type buried layer (I-Fray 2
1F part), 16... Oxide film, 17... Isolation p-type diffusion layer, 18... Photoresist film, 19...
- Oxide film, 20...Base p-type diffusion layer, 21...Emitter n-type diffusion layer. Figure 1 Figure 4 Figure 6 Figure 10 Figure 11

Claims (1)

[Claims] 1. In forming an impurity introduction mask on the main surface of a semiconductor substrate and using the mask to introduce an impurity into the semiconductor to form an impurity introduction region in a required range,
A photosensitive resin having high heat resistance is used as the mask material of the mask, and impurities are introduced deeply into the substrate through window openings obtained by selective exposure and development treatment of the mask material. A method for manufacturing a semiconductor device. 2. The photosensitive resin having high heat resistance is a photosensitive polyimide resin, and the photosensitive polyimide resin contains a polyamic acid, a bisazide photocrosslinking agent, an amine compound having a carbon-carbon double bond, and one bond in the molecule. The method for manufacturing a semiconductor device according to claim 1, which is a photosensitive polymer composition comprising a compound containing the above hydroxyl groups and having a boiling point of 150° C. or higher at normal pressure.