JPS58184759A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the dielectric breakdown withstand voltage of a gate oxide film at the end part of its island-formed semiconductor film by a method wherein a sufficiently long oxide film is formed around the island-formed semiconductor film located on an insulated substrate without performing a high temperature oxidization treatment for a long period. CONSTITUTION:The first semiconductor film and an oxidization-resistive film are coated on the insulated substrate 1 successively, and an island-formed semiconductor film 23, having an oxidization-resistive film pattern 22 on the upper surface, is formed by performing a patterning on the above-mentioned films. The second semiconductor film is deposited on the whole surface. The second semiconductor film 25 is left on the side face of the film 23 or on the surface of the substrate 21 which is exposed on the side face of the film 23. An oxide film 26 is formed around the film 23. As a result, the dielectric breakdown withstand voltage of the gate oxide film at the end part of the film 23 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a semiconductor device having a structure in which elements are formed on an insulating substrate.

The technical background of the invention and m points in between] This cypress half 44 & device, for example S 08 (5ilic
Compared to bulk semiconductor devices using silicon substrates, semiconductor devices typified by 5apphire (onon 5apphire) have smaller stray gils between wiring and bases, between diffusion layers and substrates, etc.
In addition, since the isolation between the elements is perfect, it has the advantage of realizing high-speed operation and rapid operation.

Incidentally, the semiconductor device manufactured by SOS Fuzo is conventionally manufactured by the following method. P-type single crystal silicon on a sapphire base of 1 is grown in a vapor phase, and then patterned using an anisotropic etching method to form an island-shaped silicon film 2 with a trapezoidal cross section. form (first u
Next, a gate IIl pole 4 made of, for example, red-doped polycrystalline silicon is formed on the p-type silicon gland 2 via a gate oxide l1II3, and using this gate oxidation layer 4 as a mask, an n-type impurity is added. P-type silicon 11$lJ is doped to form n4 type source and drain regions 5.6. Next, OMD-8i01fi7 is deposited on the entire surface, and the 5i01 corresponding to the source and drain regions 5.6 is
Koshitact holes S and S are opened in a part of the membrane 7, and AI!
After coating the entire surface of the film, it is buttered to form source and drain electrodes 9. IQ is formed to produce a MOS (MOS) plunger (as shown in FIG. 1, tb+).

According to the above method, the island-shaped silicon film 2 can be separated in a quantitative process, but there are various drawbacks as follows.

has. The first drawback is the effect of an anomalous M08 transistor generated on the island-shaped silicon film 2m1 surface. This is a (111
,) This is due to the fact that the MOS) transistor with plane orientation has more S iS r OH fields fIie orientation than the (100) orientation. This strange MO8 transistor effect causes an increase in leakage current and a decrease in reliability. This is due to the fact that the sapphire substrate 1 does not grow uniformly and becomes thin near the interface of the sapphire substrate 1. This is thought to be due to the lack of # at the interface of the sapphire substrate 1 at the end of the isolated island-like silicon film 2.

- 10,000, Another method for manufacturing a MOS transistor with an SOS structure is known, which is a separation technique using selective enemy formation as follows. First, a p-type single-crystal silicon film is vapor-phase grown on a sapphire substrate, and after forming an oxide film and a silicon nitride film with resistance to heat on the silicon, the silicon nitride film, which will become an element isolation region, and The oxide film is sequentially patterned to form a silicon nitride film pattern 12 and an oxide film pattern 13, respectively. Subsequently, the silicon nitride film pattern 12 is heat-treated in a high temperature oxygen atmosphere to make it resistant to corrosion, and field oxidation i1 (element isolation region) is performed.
14 to make an island-shaped silicon $15 (Fig. 83 (
a1 shown). Next, after removing the silicon nitride film pattern 12 and the oxide film pattern 13, an M08 transistor is fabricated on the island-shaped silicon GIS in the same manner as described above.
(Illustrated in FIG. 3(b)).

Although the above-mentioned method can improve the above-mentioned decrease in dielectric breakdown voltage of the gate oxide film O, it has the following drawbacks.

■ Because it requires heat treatment at high temperature and for a long time to form a thick field solder 14, a large amount of interface 4 is formed in the direction between the silicon film 15 and the sapphire substrate 1 due to auto-doping of Aj from the sapphire ridge 1. In particular, when a transistor is formed on the island-shaped silicon barrier 15, the source and drain regions 5.6 are exposed to the above voltage regardless of the voltage applied to the gate voltage li4. Conducting through the interface, a so-called back channel effect occurs.

(2) After the field oxide film 14 is formed, strong stress is generated under the silicon nitride film pattern 12, especially in the vicinity of the thick field oxide film 14, inducing crystal defects in the silicon layer 15. This causes deterioration of device characteristics, particularly an increase in leakage am.

(2) When forming the thick field oxide 11414, the oxidation progresses from the lateral direction below the silicon nitride pattern 12, and the device size becomes smaller. This requires a margin in mask dimensions, which in turn becomes an obstacle to miniaturization of element dimensions and inter-element dimensions.

[Purpose of the invention]

The present invention aims to provide a method for manufacturing a semiconductor device that improves the breakdown voltage of the insulation at the end of an island-shaped semiconductor film without performing a high-temperature, long-term thermal oxidation treatment. be.

[Summary of the Invention] The present invention includes a step of sequentially coating an insulating substrate with a first semiconductor film and an oxidation-resistant film, and patterning these films to form an island-shaped semiconductor film having an oxidation-resistant film pattern on the upper surface. a step of leaving a second semiconductor yst on the side surface or 1411 plane of this island-like semiconductor film and the surface of the produced insulating substrate; and a step of saponifying the remaining second semiconductor film to form a layer around the island-like semiconductor film. By forming an oxide film on the
Aoko aims to improve the dielectric breakdown voltage of the gate oxide film at the end of the island-shaped semiconductor film without performing long-term thermal oxidation treatment.

[Embodiments of the invention]

Next, an example in which the present invention is applied to manufacturing an fn channel MO8LSI will be described with reference to sections.

Example 1 (1) First, an insulating group &, □′1. For example, a p-type single crystal silicon film (first semiconductor film) was grown in a vapor phase on a sapphire substrate 21, and a silicon oxide film was then deposited on the silicon film. Next, apply silicon nitride pus, +
After forming a plurality of silicon nitride film patterns 22...tubes by patterning using a photoetching technique using a gas paste activating/etching method (RIg method), photoetching is further performed using an OCZffi gas IE method. An island-shaped silicon 1sj is created by patterning the silicon film using M technique and has multiple @ planes that are almost straight! ... was formed (as shown in Figure 4, ta)).

(if) Next, a thin undoped polycrystalline silicon S (20th half-body) 24 was deposited on the entire surface (Fig. t of II4).
b+Illustrated). Subsequently, the polycrystalline silicon film 24 was etched by RIE using 0.01 mFm gas, which etches in a direction perpendicular to the main surface of the substrate 21, to the extent of S*. At this time, as shown in FIG.
5 remained. Subsequently, heat treatment was performed in a commercial acid atmosphere to completely oxidize the remaining polycrystalline silicon layer 25, and an oxide film 26 was formed around the island-like silicon layer 23 (Fig. 4). (d) As shown). In this step, since the upper surface of the island-shaped silicon flJ23 is held by the oxidation-resistant silicon V film pattern 22,
It was able to prevent it from being oxidized.

(...) Next, after removing the silicon nitride gland pattern 22..., a thermal oxide film is grown on the surface of the island-like silicon film 23..., and an arsenic-doped polycrystalline silicon film is further deposited on the entire surface. did. Next, the arsenic-doped polycrystalline silicon film is patterned to form gates 4 and 27, and using this as a mask, the thermal oxide film is selectively etched to form gate oxide 1112B. Riju 27...
Using . as a mask, n-type impurities, such as arsenic, were ion-implanted into the p-type silicon islands 23, and activated to form n4-type regions 29, which become source and drain regions.

Continuing, the entire surface 4C0VI)-8i O! ! l!
After depositing 30K and opening contact holes 31..., Mt*+ islands are deposited on the entire surface, and this is patterned to take out sources, drains, etc. 1t1i2? l1412
... was formed to produce an n-channel Mo5LSI (Figure 4, te1, box).

According to the present invention, the island-like silicon film 23 having the oxidation-resistant O-silicon nitride film pattern 22 on the upper surface.
...In order to leave polycrystalline silicon H2s... on the side surface and thermally oxidize this remaining polycrystalline silicon yyzs...
Island-shaped silicon #23... without oxidizing IJI, island-shaped silicon film 23... is processed by thermal oxidation treatment for one hour.
- A sufficiently thick oxide film 26 can be formed around the periphery. Immediately
The time required for oxidation is approximately 25.
It is determined by the thickness of the polycrystalline silicon@
1+4 of XS... is the oxide film 26 after oxidation is M
It is sufficient to withstand the operating voltage V of O8I, 8I (a few hundred or more is sufficient, so the oxidation time can be greatly shortened compared to the conventional selective polishing method. For example, 500Ie
The time required to oxidize the remaining polycrystalline silicon oxide 25 is only about 20 minutes at a temperature of 950° C., which can be shortened by more than an order of magnitude compared to the 4-type selective oxidation method. 500 Ie (D residual polycrystalline silicon 25...
・Considering that the film thickness of the gate oxide film is 5001e or less in 10001eali Tona iJ, now 4 (7) L8I, the dielectric breakdown voltage of the gate oxide film is The same can be achieved with the oxide film 26.

As mentioned above, since the thermal oxidation time can be changed over a wide range, autodoping of A/ from the sapphire substrate 21 can be suppressed, and as a result, the sapphire substrate 21 and the island-like silicon group 23
It is possible to effectively prevent back channel effects caused by deterioration of the interface with... In addition, the island-like silicon film 23...
Since the initial dimensions are ensured even after the oxide film 26 is formed, it is possible to manufacture a high-density MO8LSI. Furthermore, since oxidation hardly progresses under the silicon nitride film pattern 22...edge, crystal defects due to stress that are melted by the selective oxidation method do not occur, and high-performance MO8LSI with low leakage current can be realized. Obtainable.

In addition, if the silicon gland fi'RIEg↓resify 7 substrate 21 is etched approximately perpendicularly, (100)
An island-like silicon film 23 having 11 planes can be formed, and as a result, the 884-8in interface level can be lowered.

Note that in the first embodiment, the remaining polycrystalline silicon film 2
5... was heated to form oxidized $26..., but as shown in Figure 5, the island-like silicon group 23...114
Oxidized flp26' may be formed by performing thermal oxidation treatment so that a part of 11thi is also oxidized.

Further, as shown in FIG. 6(a), instead of the undoped polycrystalline silicon film, a boron-doped polycrystalline silicon film 33 is deposited over the entire surface, and then this is etched by etching to form an island-like silicon-2J film. The boron-doped polycrystalline silicon remains on the @ surface.

This is then thermally oxidized to create island-shaped silicon WI! 23 Forms an oxide film 26 around the silicon island and diffuses boron into the side surface of the silicon island 23 to form a p' type region 34
By using a boron-doped polycrystalline silicon film in this way, it is possible to form a p0 type region 34 that functions as a channel cut between the source and drain, and the oxidation rate can be determined. As a result, the thermal oxidation time can be further shortened.

-, as shown in FIG. 7(a), the island-shaped silicon film 23 is
It is also possible to adopt a method of forming a thin oxide film 35 on the 1141J plane of .

In addition, a polycrystalline silicon group was deposited on all songs, and this was thermally oxidized to convert it into an oxide film, and then the oxide film was etched using the ftRIB method, leaving an oxide film around the side surfaces 8 of the island-shaped silicon film. Good too.

Example 2 (1) Similar to Example 1, polycrystalline silicon #2 is applied to the entire surface of the sapphire substrate 21 on which the island-shaped silicon layer 23 with the silicon nitride film pattern 722 is formed on the earthwork 1.
4 (as shown in Figure 8).

Next, a photoresist film was applied to the entire surface. At this time, as shown in FIG.
A thick photoresist film 36m is applied to the side steps and the short distance between the island-shaped silicon films 23, 23, and the polycrystalline silicon film 24 corresponding to the protruding silicon nitride film patterns 22... Thin photoresist 1lis6 on top
b were covered with upper cloth (as shown in FIG. 8(b)). Subsequently, the photoresist film was gradually etched using, for example, O plasma until the surface of the protruding polycrystalline silicon layer 24 was exposed. As a result, a seven-layer photoresist layer 36 remained between the island-like silicon films 23 and 21 (as shown in FIG. 8C).

Next, using the remaining photoresist film 36 as a mask, the polycrystalline silicon film 24 is selectively etched to leave the polycrystalline silicon film 31 around the island-shaped silicon fj 23 and on the knee portion of the sapphire substrate. The resist $36f was removed (as shown in FIG. 8, 1d)). Subsequently, the remaining polycrystalline silicon film 37 is heat-treated in a high-temperature acidic atmosphere to obtain island-like silicon p! ! 2J... Oxidized @SS was formed on the sapphire substrate 21 exposed to the surroundings (8th
Figure (・) Illustrated). 11'(Ill
Next,! Il+! As in Example 1, the silicon nitride film patterns 22... are removed, and the gate electrodes 27... are formed on the silicon islands 21 via the gate oxide films 2 and...
, n4″ type region 29..., 0VD-810,
Membrane 80. Contact hole 31..., person arrangement ssλ
... was formed to produce an n-channel MOS L 8X (as shown in FIG. 8(f)). MO produced in this way
8L8I had the same effect as Example 1.

Example 3 (:) First, a p-type single crystal silicon film was grown in vapor phase on the sapphire base IPj21, and a silicon nitride film and a phosphorus silicide glass 1I (P8G film 1) were sequentially deposited on this silicon film. Next, the P2O film and silicon V conversion part a)'
; 4+H, pattern en/L, psog pattern 39.
. . . A silicon nitride film pattern 22 . . . is formed, and the exposed silicon film is then patterned by photo-etching technology using the RIB method using CC6 gas to form island-shaped silicon! i1!23... was formed (as shown in Figure 's9 (a)).

(II) Next, an undoped polycrystalline silicon film 24 was deposited on the entire surface and then heat treated in a nitrogen atmosphere. At this time, as shown in FIG. 9(b) (P80I! Pattern 39
... Phosphorus is diffused into the surrounding polycrystalline silicon @j (phosphorus-doped polycrystalline silicon 11! region 40).Subsequently, the etching rate of the phosphorus-doped polycrystalline silicon is lower than that of the undoped polycrystalline silicon. Taking advantage of the fact that it is more than twice as hot, OF4+H and gas plasma etching selectively removes the P8G pattern S9...surrounding Lindor polycrystalline silicon region 4Q! An undoped polycrystalline silicon film 41 was left on the exposed sapphire substrate 21 (as shown in Figure 911(c)).Subsequently, after removing the PSG# patterns 39..., the remaining polycrystalline silicon s!41 was removed. An oxide film 42 was formed on the sapphire substrate 21 which was exposed to the surroundings of silicon island 31135 by heat treatment in a hot oxygen atmosphere (FIG. 9(d)).
(Illustrated).

(+i+) Next, as in Example 1, the silicon nitride film pattern 22... is removed, and the island-shaped silicon ylxs
. . . A gate electrode 2I . . . is formed thereon via a gate oxide film 2r .
8'i0@waist? 6. Contact hole 31..., At
Form Wij32... and n channel M<, +8
An LSI was manufactured (as shown in Figure 9). The MO8L8I thus left behind had the same effects as in Example 1.

In addition, in the above-mentioned Examples 2 and 3, a modification of Example 1 (
5 to 7), island-shaped silicon il! Oxidize even a part of the surface, or replace the p-type region with an island-like silicon film l11.
It may be formed on one surface, or an oxide film may be formed on the 784214 surface of the silicon island in advance. Polycrystalline silicon film (second
Amorphous silicon may be used instead of the semiconductor 1i1.

Embodiments 1 to 3 described above are examples applied to n-channel MO8LSI, but p-channel MO8LSI
, 0M08LSI, etc.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to form an oxide film of sufficient thickness around the island-shaped semiconductor layer on the insulating substrate without performing high-temperature, long-term thermal oxidation treatment, and thereby It is possible to improve the dielectric breakdown voltage of the gauge oxide film at the edge of the film, suppress the occurrence of leakage current due to deterioration at the interface between the insulator 1 temporary and the island-like semiconductor film, and achieve remarkable results such as speeding up the achievement of higher density. It is possible to provide an effective method for manufacturing a semiconductor device.

[Brief explanation of the drawing]

Figure 1 (al, tb) was separated by conventional air insulation. Channel MOf9) Cross-sectional view showing the manufacturing process of transistor O, Fig. 2 is Fig. 1<aJ, (b)
A cross-sectional diagram to explain the problems caused by the manufacturing method of
Fig.fa) *tb)F'i Fig. 4 (a) to (e) tri
Cross-sectional view showing the manufacturing process of n-channel MO8L8I in Example 1 of the present invention, FIG. 5, -16:1. , Figure (1
) *(b) and FIGS. 7(a) e cb) are cross-sections showing a modification of Example 1, and FIGS. Shingaen, wc9 (al~(cl) is a sectional view showing the manufacturing process of n-channel MO8L8I in Example 3 of the present invention. 21...Sapphire substrate, 22...Silicon nitride film pattern , 23...p-type island silicon film, 24.
...Polycrystalline silicon film, 2M, 37.41...Remaining polycrystalline silicon film, 26.26', 3B-42...
・Thick oxide film, 27... Gate electrode, 28... Gate oxide film, 29... Male seed region, 32... A/wiring,
36...Residual photoresist waist, 39...PEG exhibition pattern. Transfer agent Bensakashi Suzue Takehiko：′：

Claims (4)

[Claims] (1) A step of sequentially coating the first semiconductor film and a 1 m oxidizing film on the insulating base sand, and a step of patterning these layers to form an island-shaped semiconductor film having an oxidation-resistant film pattern on the upper surface. And one side of this island-shaped semiconductor surface or @
a second semiconductor film remaining on the surface and the exposed insulating radix surface; and a step of oxidizing the remaining second semiconductor film to form an oxide film around the island-shaped semiconductor film. A method for manufacturing a featured semiconductor device. (2) After covering the entire surface with the second semiconductor film, leave the second semiconductor film on the side surface of the island-shaped semiconductor film or the exposed insulation 411!2 table (3). A method for manufacturing a semiconductor device according to item 1, characterized in that the semiconductor film is etched by hexagonal etching such as active ion etching or ion beam etching. (3) The step of leaving the second semiconductor film on the side surface of the island-shaped semiconductor film and the extended surface of the insulating substrate is performed by coating the entire surface including the oxidation-resistant film pattern with the second semiconductor, and then coating the second semiconductor film with an organic resin film. The area on the oxidation-resistant film pattern is thinner than other areas, and this organic resin film is applied until the second semiconductor film portion corresponding to the oxidation-resistant ℃ pattern extends. 1. A manufacturing method according to claim 1, wherein the second semiconductor film is etched using the remaining organic resin film as a mask after removal. (4) The step of leaving the second semiconductor group on the side surface of the island-shaped semiconductor film and the extended surface of the insulating substrate is performed by forming an impurity-containing film pattern on the oxidation-resistant gland pattern of the island-like semiconductor film, and forming the film pattern A second semiconductor film portion in which the impurities have been diffused; A method for manufacturing a semiconductor device according to item 1 of the IFF claim, characterized in that the method is carried out by selectively etching.