JPS58164226A - Etching of semiconductor substrate - Google Patents

Abstract

PURPOSE:To obtain a pattern having high precision and favorable yield by a method wherein a metal element layer having the desired pattern is formed on a semiconductor substrate according to the irradiation of an ion beam, and the plasma etching process is performed using the layer thereof as the mask. CONSTITUTION:The semiconductor substrate 13 is accommodated in a vacuum vessel 12 whose inside is formed in the vacuum condition according to an exhaust tube 11, and the metal element layer 16 is formed on the substrate 13 according to the metal element ion beam 15 sent from a converging ion beam source 14 positioned at the upper part of the substrate thereof. At this time, Si is used for the substrate 13, and moreover Al ions are used for the ion beam 15. Then gas 18 for plasma etching consisting of CF4 is sent in the vessel 12 through a leading-in tube 17, the inside of the vessel 12 is converted into the plasma condition according to a high-frequency coil 19 provided at the outside circumference of the vessel 12, and the recessed part of the desired pattern is generated in the substrate 13 using the element layer 16 as the mask.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor substrate etching method for etching a semiconductor substrate into a desired pattern.

Conventionally, as shown in FIG. 1, a semiconductor substrate 1 to be etched is etched in advance.
Prepare (Fig. 1A), and then on the semiconductor substrate 1,
A photoresist layer 2 is coated (FIG. 1B), and an exposure mask 3 having a desired pattern obtained in advance is positioned and arranged on the photoresist layer 2 (FIG. 1C).
Next, the photoresist layer 2 is exposed to light 4 through the exposure mask 3 (FIG. 1D), and then the exposed photoresist layer 2 is developed using a developer. The exposed area or the unexposed area of the photoresist 12 is dissolved away, and the pattern of the exposure mask 3 is formed by the exposed area or the unexposed area of the photoresist 12. A mask layer 5 having a pattern corresponding to that shown in FIG. A method has been proposed in which the mask @5 is then removed from the semiconductor substrate 1 (FIG. 1G) and the semiconductor substrate 1 is etched into a desired pattern.

However, in the case of the conventional etching method for semiconductor substrates, it is necessary to prepare an exposure mask 3 in advance, and there is a step of coating the photoresist layer 2 on the semiconductor substrate 1, and a step of applying the exposure mask 3 on the photoresist layer 2. A step of positioning and disposing, a step of exposing the seven photoresist layers 2 on the semiconductor substrate 1, a step of developing the exposed photoresist layer 2 to form the mask 115, and an etching step for the semiconductor substrate 1. Many steps are required, including a processing step and a step of removing the mask layer 5.
This method has the drawback that the semiconductor substrate 1 cannot be easily etched into a desired pattern with high precision and good yield.

Therefore, the present invention proposes a novel method for etching a semiconductor substrate free from the above-mentioned drawbacks, which will become clear from the detailed description below.

As a result of various experiments, the present inventors found that A1. Ga, Ba, Be, ca, C8, Li, Mo, Na, PbPu, Rb, Sr,
When irradiated with an ion beam of metal elements such as 7n and Z, AI, Ga, Ba, etc.
, Be, Ca, Cs.

K, Li, MQ, Na, Pb, Pu, Rb, S
A layer of metal elements such as r, Zn, and Z is formed on a semiconductor substrate of <Si.

Ga, Ba, Be, Ca, Cs, Li, Ma, N
In a state where a layer of metal elements such as a, Pb, Pu, Rb, Sr, Zn, and 7r is formed, CF, C2F6, C3F,
If plasma etching treatment is performed using a plasma etching gas such as gas, AI, Ga, Ba,
Be, Ca.

Cs, Li, Ma, Na, Pb, Pu, Rb, 3r
, 7n and Z'', etc., a semiconductor substrate made of Si, etc. is etched, and a semiconductor substrate made of Qa AS, 10P, etc. is etched using a layer of metal elements such as Cs, K, Li, MIJ, xa, R
If ion beams of metal elements such as b and Cd are irradiated, Li, M
o, Na.

A layer is formed of metal elements such as Rb and Cd, and C is formed on a semiconductor substrate made of GaAs, in P, etc.
s, Li, Mg, Na, Rb.

C and C to the semiconductor substrate made of GaAs, lnP, etc. in a state where a layer of metal elements such as CD is formed.
If plasma etching treatment is performed using a plasma etching gas such as CI, CH3Cl gas, Cs,
Li, Mo.

It has been confirmed that a semiconductor substrate made of GaAs, InP, etc. can be etched by using a layer made of metal elements such as Na, Rb, and Cd as a mask.

Therefore, the present inventor has proposed the invention described in the claims as the present invention.According to the present invention, a semiconductor substrate is irradiated with an ion beam of a metal element. The semiconductor substrate is then subjected to a plasma etching process, which is an extremely simple process.Therefore, the semiconductor substrate can be formed into a desired pattern without requiring many steps as in conventional semiconductor substrate etching methods. It has the great feature that it can be etched with high precision and high yield.

Next, an example of the present invention will be described.

Example 11 As shown in FIG. 2, the inside of the vacuum container 12 is evacuated through the exhaust pipe 11 to create a vacuum state, and in advance,
With the semiconductor substrate 13 as shown in No. 318 arranged, an ion beam 15 of a metal element is obtained in the vacuum container 12 from the focused ion beam source 14 provided in the vacuum container 12. was irradiated onto the semiconductor substrate 13 in a desired pattern.

In this case, the semiconductor substrate 13 was made of Si, and the ion beam 15 of the metal element was an ion beam of A1.

At that time, a layer 16 of the metal element was formed on the semiconductor substrate 13 in the region irradiated with the ion beam 15 of the metal element, as shown in FIG. 3B. In this case, the ion beam 1116 of the metal element is the ion beam 15 of the metal element.
Since it was an ion beam of A1, it was formed as a layer of A1.

Next, the etching gas introduction pipe 17 is inserted into the vacuum container 12.
A plasma etching gas 18 is introduced through the vacuum chamber 12, and a high frequency wave for plasma generation is applied to the high frequency coil 19 for plasma generation disposed around the plasma etching gas 18. It turned into plasma.

In this case, Ct=
4 gas was used.

In such a case, a large amount of free radicals of F is generated in the vacuum container 12, and the free radicals of F and AI that constitute the layer 16 made of the metal element cause AI +3F → AlF3 .・(
3i +4F → SiF4 due to the free radicals of Sl and F that constitute the reaction in the region of the semiconductor substrate 13 other than the region where the layer 16 made of the metal element is formed. ↑・・・・・・・・・
・(2) occurs, and in this case S i F of equation (2)
Since 4 has a much higher vapor pressure than AlF3 in formula (1), the region where the metal element 16 of the semiconductor substrate 13 is not formed is plasma etched. , the semiconductor substrate 13 was etched as shown in FIG. 3C.

In this way, the semiconductor 113 could be etched into the desired pattern.

Example 2 The ion beam 15 of the metal element was replaced with an ion beam of AI, including Ga, Ba, Be, and Ca.

Cs, Li, Ma, Na, Pb, Pu, Rb, 3r
The same steps as in Example 1 were followed except that one ion beam in , 7n and Zr was used.

In such a case, the detailed explanation will be omitted, but in accordance with the case of Example 1, the metal element forming @16 formed on the semiconductor substrate 1 and the free F (1
) reaction according to the formula and (2) described above in Example 1.
The semiconductor substrate 13 is etched by a mechanism in which a reaction similar to that shown in the equation occurs, and the region of the semiconductor substrate 1 other than the region where the layer 16 of the metal element in this case is formed is etched.
could be etched into the desired pattern.

Example 3 The same steps as in Example 1 were followed except that the plasma etching gas 18 was one of C, F, 03 Fg gases instead of CF gas.

In such a case, the semiconductor substrate 13 could be etched into a desired pattern using the same mechanism as in Example 1, although a detailed explanation will be omitted.

Example 4 The metal element ion beam 15 was replaced with an AI ion beam, and Qa, Ba, [3e, Ca, C
a, Li, MO, Na, Pb, Pu, Rb.

One ion beam in Sr, Zn and Zr was used, and the plasma etching gas 18 was replaced with CF gas, C
The same steps as in Example 1 were followed except that 16 F, 03 F, gases were used.

In such a case, the semiconductor substrate 13 could be etched into a desired pattern using a mechanism similar to that of Example 1, although a detailed explanation will be omitted.

Example 5 The semiconductor substrate 13 was made of Ge instead of Si, and the ion beam of a metal element was replaced with an ion beam of AI.
a, Ba, Be, Ca, Ca, Ni, L
i, tvlo, Na, Pb, Pu, Rb.

One of Sr, Zn, and Zr was used, and the plasma etching gas 18 was replaced with CF+ gas, and C2F6.0
Example 1 except that one in 3F5 gas was used.
The same process as in the case was taken.

In such cases, the detailed explanation will be omitted, but the semiconductor substrate 13 made of Ge in this case could be etched into the desired pattern using a mechanism similar to that of Example 1.

Example 6 The semiconductor substrate 13 is made of GaAs instead of Si, and the ion beam 15 of two metal elements is
Instead of the A1 ion beam, a C8 ion beam is used, and the plasma etching gas 18 is CF4.
Except that CCl4 gas was used instead of gas.
The same steps as in Example 1 were followed.

In such a case, a detailed explanation will be omitted, but a large amount of free radicals of CI are generated in the vacuum container 12 while the layer 16 of the metal element C8 is formed on the semiconductor substrate 13. Based on this, a reaction of Cs + C1 → Cs C1 (3) occurs between Cs constituting the metal element layer 16 and free radicals of CI, and the reaction of Cs + C1 → Cs C1 (3) occurs, and Layer 1 with metal elements
GaAs in areas other than the area where 6 is formed
GaAs +6Cl → GaCl3 ↑+AsCl3 ↑・・・・・・・・・(
4) reaction occurs, in this case GaCl3 and AsCl
3 has a significantly higher vapor pressure than that of CsCl, so that the region of the semiconductor substrate 13 other than the region where the layer 16 of the metal element is formed is etched. The semiconductor substrate 13 could be etched into the desired pattern.

Example 7 The semiconductor substrate 13 was replaced with a semiconductor substrate made of GaAs,
The same steps as in Example 6 were followed except that the semiconductor substrate was made of InP.

In such a case, the detailed explanation will be omitted, but in accordance with the case of Embodiment 6, in the vacuum container 12, C3+C1→CsC
1・・・・・・・・・(5)In P+4C1→In
The reaction C1↑+P CI3 ↑・・・・・・・・・ (6) occurs, and in this case, In CI and PCl3 have much higher vapor pressure than CsCl, so that the semiconductor substrate The semiconductor substrate 13 could be etched into a desired pattern using a mechanism in which regions other than the region where the layer 16 of the 13 metal elements was formed were etched.

Example 8 The same steps as in Example 6 were followed except that the plasma etching gas 18 was CH3Cl gas instead of CC14 gas.

In such a case, the semiconductor substrate 13 could be etched into a desired pattern using the same mechanism as in Example 6, although a detailed explanation will be omitted.

Example 9 Example 7 except that the plasma etching gas 18 was replaced with C C 14 gas and CH3Cl gas.
The same process as in the case was taken.

In that case, the semiconductor substrate 13 could be etched into the desired pattern using the same mechanism as in Example 7.

Example 10 Same as in Example 6 except that the metal element ion beam was replaced with a C3 ion beam and one ion beam among K, Li, MO, Na, Rb, and Cd was used. The process was followed.

In such a case, a reaction similar to that in Example 6 between the metal element constituting the layer 16 of the metal element in this case and C1 in this case and the semiconductor substrate 13 in this case are performed in the vacuum container 12. A reaction similar to that in Example 6 occurs between GaAs and 01 in this case, and the region of the semiconductor substrate 13 in this case other than the region where the layer 16 made of the metal element in this case is formed. The semiconductor substrate 13 could be etched into a desired pattern using the mechanism in which the semiconductor substrate 13 was etched.

Example 111 The same steps as in Example 10 were followed except that the semiconductor substrate 13 was made of InP instead of GaAs.

In such a case, a reaction according to Example 7 between the metal elements constituting 1i16 made of metal elements in this case and CI in this case and the semiconductor substrate 13 in this case are performed in the vacuum container 12.
A reaction similar to that in Example 7 occurs between InP constituting 01 in this case, and the semiconductor substrate 13 in this case
In this case, the semiconductor substrate 13 could be etched into a desired pattern by etching the region other than the region where the layer 16 of the metal element was formed.

Example 12 Example 10 except that the plasma etching gas 18 was CH3Cl gas instead of C, C14 gas.
The same process as in the case was taken.

In such cases, detailed explanation will be omitted, but Example 10
The semiconductor substrate 13 could be etched into a desired pattern using the same mechanism as in the case of .

Example 13 The same steps as in Example 11 were followed except that the plasma etching gas 18 was CH3Cl gas instead of CCl4 gas.

In such cases, detailed explanation will be omitted, but Example 11
The semiconductor substrate 13 could be etched into a desired pattern using the same mechanism as in the case of .

Incidentally, the above description has only shown a few embodiments of the present invention, and the semiconductor 113 is a semiconductor substrate made of a group III semiconductor other than Si or Qe, and the steps similar to those of Embodiments 1 to 5 are adopted. It will be clear that the semiconductor substrate 13 in this case can be etched into any desired pattern.

In addition, the semiconductor substrate 13 is made of a material other than GaAs or InP, generally Ga, -In, As, -, p, (however, 0
A semiconductor substrate made of a semiconductor represented by ≦X≦1.0≦■≦1) is used, and the semiconductor substrate 13 in this case is etched into a desired pattern using steps similar to Examples 6 to 13. It is clear that it can be done.

Further, ions of metal elements (-15) are added to the semiconductor substrate 13.
AI, Ga, Ba, B depending on the semiconductor that makes up the
e, Ca, Cs, I-i, Mo.

A metal ion beam other than one of Na, Pb, Pu, Rb, 3r, Zn and Zr, or Cs, Li,
M (1, Na, Rb, and Cd), and the plasma etching gas 18 may be C
F4゜02F,, C, F1? Carbon fluoride gas or similar gas other than one in the gas or CCl4.0
It is clear that a semiconductor substrate can be etched into a desired pattern by using a chloride gas or a similar gas other than one of the H3CI gases and by following a process similar to the example described above. Dew.

Various other modifications may be made without departing from the spirit of the invention.

[Brief explanation of drawings]

FIGS. 1A-1G are cross-sectional views showing sequential steps in a conventional semiconductor substrate etching method. FIG. 2 is a diagram showing an embodiment of the method of etching a semiconductor substrate according to the present invention, together with a sectional view of an apparatus used therein. FIGS. 3A-3C are cross-sectional views showing sequential steps in an embodiment of the method of etching a semiconductor substrate according to the present invention. 12・・・・・・・・・・・・Vacuum container 13...
...... Semiconductor substrate 14...
......Focused ion beam source 15...
......Ion beam of metal elements 16.
・・・・・・・・・・・・ Layer 18 with metal elements
・・・・・・・・・・・・・・・Plasma etching gas 19・・・・・・・・・・・・・・・High frequency coil for plasma generation

Claims (1)

[Claims] A layer of the metal element is formed in a desired pattern on the semiconductor substrate by irradiating the semiconductor substrate with an ion beam of the metal element, and then a plasma etching process is performed on the semiconductor substrate using the layer of the metal element as a mask. A method for etching a semiconductor substrate, comprising etching the semiconductor substrate as described above.