JPH04241419A - Etching substrate holding cassette - Google Patents

Abstract

PURPOSE:To prevent the destruction of a substrate during an etching process. CONSTITUTION:The damage of patterns on substrates is prevented by providing a cassette supporting body 4 having a recessed section in which an etching liquid 7 for dipping an etching substrate 2 is contained and a flexible sealing member which is housed in the body 4 and, at the same time, holds the substrate 2 by the outer peripheral section of the substrate 2 so that the pattern forming surface of the substrate 2 cannot come into contact with the etching liquid 7.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching substrate holding cassette that is used in chemical etching in which only one side of an etching substrate is processed and the other side must be held in a non-contact state.

0002

[Prior art] Generally, S uses an alkaline chemical solution.
In anisotropic etching, a method is used in which a nitride or oxide film is formed over the entire Si substrate, the nitride film is removed only in the area to be etched, and the entire Si substrate is immersed in an etching solution. There is.

0003

[Problems to be Solved by the Invention] However, when thinning a Si substrate on which a fine metal pattern has already been formed on one side by anisotropic etching from the other side, conventional In this method, the pattern is damaged by direct contact with the etching solution. Even if a suitable substrate holding jig is used to avoid such problems, if the pattern forming part comes into contact with a part of this jig, it may be damaged or the sealing of the jig against the Si substrate may be affected. If this is not sufficient, a problem arises in that the etching solution permeates during etching and damages the pattern. Furthermore, with this type of etching, the thickness of the substrate in the pattern formation area can be reduced by several micrometers.
If the thickness of the substrate must be reduced to less than m, the mechanical strength of the thinned substrate is significantly reduced, and there is a problem that this portion may be destroyed during etching. Although the case of anisotropic etching using an alkaline chemical solution has been described above, the same problem also occurs in isotropic etching using a mixed acid of hydrofluoric acid and nitric acid.

Therefore, an object of the present invention is to provide an etching substrate holding cassette that can prevent substrate destruction during etching.

[0005]

[Means for Solving the Problems] In order to achieve the above object, a first etching substrate holding cassette according to the present invention includes a concave cassette support in which an etching solution is accommodated and in which the etching substrate is immersed; The sealing material is housed in the cassette support and has flexibility to hold the outer periphery of the etching substrate so as to keep the pattern-formed surface of the etching substrate out of contact with the etching solution. Further, the second etching substrate holding cassette according to the present invention is formed in a cassette support facing the etching substrate in addition to the first etching substrate holding cassette, and applies preload to a non-contact portion of the pattern forming surface of the etching substrate. It is provided with a pre-pressure chamber and a pressure supply means for supplying an appropriate pressure to the pre-pressure chamber. Further, the third etching substrate holding cassette according to the present invention is provided with a pressure adjusting means for always adjusting the pressure of the etching solution and the pre-pressure to be equal in addition to the second etching substrate holding cassette.

[0006]

[Operation] In the first aspect of the present invention, the etching solution is prevented from penetrating by keeping the pattern-formed surface of the etching substrate in a non-contact state. Further, in the second invention, destruction of the etching substrate during etching is prevented by applying preload to the non-contact portion of the pattern forming surface. Furthermore, in the third invention, a preload of the same magnitude is applied from the opposite side of the etching substrate to the liquid pressure acting on the etching surface of the etching substrate, and fluctuations in the pressure balance are suppressed during etching.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings. (Example 1) FIG. 1 shows the first example of the etching substrate holding cassette according to the present invention.
FIG. In the figure, first, as shown in figure (a), a metal pattern 3 is formed on one side of a Si substrate 2 on which a nitride film 1 is formed.
The i-substrate 2 is placed with the surface on which the metal pattern 3 is formed facing downward so as to face the bottom surface inside the cassette support 4, and its peripheral portion is held by the sealing material 5a. Next, this S
A sealing material 5b is installed along the outer periphery of the i-board 2, and as shown in FIG. and fix it. At this time, the sealing material 5a and the sealing material 5b are S
The i-substrate 2, the cassette support 4, and the cylinder 6 are deformed so as to be in complete contact with each other. Even if the etching liquid 7 is supplied into the cassette support 4 in this state, the etching liquid 7 will not penetrate into the back surface of the Si substrate 2, and the metal pattern 3 is also held in a non-contact state. The desired etching can be performed without causing any damage to 3. Note that the sealing materials 5a and 5b include
It is of course important to have corrosion resistance against the etching solution 7, but it is also important that when an appropriate stress is applied, it can be easily and reasonably deformed and adhered to the Si substrate 2, while at the same time applying an even stress to the Si substrate 2. It is necessary to have appropriate flexibility and shape. Here, sealing materials 5a and 5b
Since the flexibility and shape of are complementary to each other,
There is no need to specifically limit the flexibility and shape. For example, in the case of a material with poor flexibility, a shape that is easily deformed may be used, and in the case of sufficient flexibility, a simple shape may be used.

FIGS. 2(a) and 2(b) are cross-sectional views showing the structure of another embodiment of the sealing material applied to the etched substrate holding cassette according to the present invention, and the same parts as in the previous figures are denoted by the same reference numerals. is attached. In this figure, the difference from FIG. 1 is that the sealing material 5 is integrally constructed from one part, and since this sealing material 5 has the same properties as described above, this case is also the same as in FIG. 1. can be etched. This result shows that there is no need to limit the shape of the sealing material 5. In the etched substrate holding cassette having the structure shown in FIGS. 1 and 2, the air trapped between the Si substrate 2 and the cassette support 4 cannot move anywhere, so the etched portion of the Si substrate 2 is From below, it receives liquid pressure corresponding to the depth from the surface of the etching liquid 7, and from below it receives air pressure that expands depending on the temperature of the etching liquid 7, and the difference between the two becomes stress acting on the Si substrate 2. . On the other hand, as the etching progresses, the thickness of the etched portion of the Si substrate 2 becomes thinner and the mechanical strength thereof also decreases. If the stress acting on this etched portion becomes greater than the mechanical strength, the Si substrate 2 will be destroyed at that point. Furthermore, when fixing the Si substrate 2 in the cassette support 4, if a gap exists between the Si substrate 2 and the sealing material 5 due to misalignment or damage to the sealing material 5, this may occur. A problem arises in that the etching solution 7 seeps into the surface. That is, Example 1
The etching substrate holding cassette is effective when the thickness of the Si substrate 2 to be thinned by etching is not very thin, for example, when the thickness is 50 μm or more.

(Embodiment 2) FIG. 3 is a sectional view showing the structure of a second embodiment of the etching substrate holding cassette according to the present invention, and the same parts as in the previous figures are given the same reference numerals. This figure differs from FIG. 1 in that a pre-pressure chamber 8 and a gas introduction hole 9 are provided at the bottom of the cassette support 4 facing the Si substrate 2;
A valve 10 communicating with the gas introduction hole 9 and a pressure gauge 11 are connected to the outside of the gas inlet 9 . In such a configuration,
Gas at an appropriate pressure is fed into the prepressure chamber 8 through the gas introduction hole 9, the valve 10 is closed, and the change in gas pressure is measured with the pressure gauge 11 for an appropriate time (about 3 minutes). If pressure gauge 1
If the indicated pressure 1 decreases, it indicates that there is a gap between the sealing materials 5a, 5b and the Si substrate 2, and the sealing material 5
After checking for scratches on a and 5b and for any misalignment of the Si substrate 2, place the Si substrate 2 on the cassette support 4 again. If there is no change in the pressure indicated by the pressure gauge 11, the etching liquid 7 is supplied into the cassette support 4, and at the same time, the pre-pressure is adjusted so that the etching liquid 7 opposes the pressure acting on the Si substrate 2. As a result, the stress acting on the Si substrate 2 is nullified, so there is no longer a factor that limits the thickness of the etched area. Using this etched substrate holding cassette, all the Si in the etched area can be removed to a thickness of approximately 1 μm or less. It becomes possible to perform etching that leaves only the nitride film or oxide film. In the etching substrate holding cassette of Example 2,
If the etching liquid 7 evaporates during etching and the liquid pressure changes, or if the temperature of the etching liquid 7 changes and the gas expands, the prepressure fluctuates and the balance of pressure acting on the etched area collapses. This may cause the Si substrate 2 to break.

(Embodiment 3) FIG. 4 is a cross-sectional view showing the structure of a third embodiment of the etching substrate holding cassette according to the present invention, and the same parts as those in the previous figures are given the same reference numerals. 3, the difference between the drawing and FIG. One end of the cylinder 14 is connected, and the other end of the cylinder 14 is connected to the gas introduction hole 9 via a gas flow pipe 15. Note that 16 is a liquid injection valve. In such a configuration, first, as in the second embodiment, S
Confirm that there is no air leak between the i-board 2 and the cassette support 4. Next, open the liquid injection valve 16 and pour an appropriate amount of etching liquid 7 into the cylinder 14 from the injection port (depth 1
/4), close the liquid injection valve 16 again, open the liquid valve 13, and supply a predetermined amount of the etching liquid 7 into the cylinder body 6. Thereafter, the gas valve 10 is opened to adjust the preload so that the same pressure as the pressure exerted on the Si substrate 2 by the etching solution 7 acts on the back surface of the Si substrate 2. Finally, the gas valve 10 is closed to seal the gas, and the liquid valve 13 is opened to combine the etching liquid 7 and the etching liquid in the cylinder 14. As a result, the air pressure Pa and the hydraulic pressure Pe acting on the liquid interface inside the cylinder 14 are respectively S
The gas pressure and the liquid pressure that are affecting the i-substrate 2 are equal. When the height of the etching solution 7 decreases from this state, for example due to evaporation, the hydraulic pressure Pe' exerted on the Si substrate 2 becomes smaller than the initial hydraulic pressure Pe, and the pressure balance at the interface of the cylinder 14 collapses (Pa>Pe ′), the interface moves in the downward direction. Since this lowering of the interface has the effect of increasing the gas volume and simultaneously raising the etching liquid level, the prepressure PA changes so as to be small and the liquid pressure PE to be large. When both pressures are equal,
The movement of the interface stops. The pressure at this time is PA (<Pa
)=PE (Pe′<PE<Pe). On the other hand, if the amount of the etching solution 7 does not change and the temperature decreases, the volume of the gas decreases and the preload Pa' exerted on the Si substrate 2 decreases from the initial preload. The pressure balance at is disrupted (Pa′<P
e), the interface moves upwards. This movement of the interface has the effect of reducing the gas volume and lowering the etching liquid level, so that the prepressure PA increases and the liquid pressure PE decreases. Then, when the pressures of both become equal, PA (Pa′<PA<Pa)=PE(<Pe)
The movement of the interface stops due to the relationship. According to such a configuration, even if the balance between the liquid pressure acting on the Si substrate 2 and the preload is lost due to a change in liquid volume or temperature during etching, the interface within the cylinder 14 suppresses fluctuations in the pressure balance. Since the Si substrate 2 moves in the same direction, the same pressure always acts on both sides of the Si substrate 2.

In the third embodiment described above, the case where the etching liquid 7 was supplied into the cylinder 14 was explained, but water may be supplied instead of the etching liquid 7.

Furthermore, in the third embodiment described above, a case was explained in which a method was adopted in which the pressure fluctuations acting on the Si substrate 2 were adjusted by movement of the liquid surface within the cylinder 14, but the present invention is not limited to this. Example 4
The same effect as described above can be obtained by using a method in which the liquid pressure and gas pressure acting on the Si substrate 2 during etching are directly measured using a pressure sensor, and the pre-pressure is adjusted so that both pressures are the same. .

Furthermore, in the above embodiment, the method of supplying the etching solution 7 into the cassette support 4 was explained.
As shown in FIG. 5, in the case of Examples 1 and 2, the entire substrate holding cassette is removed, and in the case of Examples 3 and 4, the liquid reservoir cylinder body is It is also possible to immerse the cassette support 4 and the cassette support 4 into the etching bath 17.

Note that the X-ray exposure mask has a structure in which a 1-mm-thick Si single crystal substrate is coated with a silicon nitride film 1 to 2 μm thick, and a metal pattern that absorbs X-rays is placed on this film. Therefore, the substrate holding cassette of this example was used to manufacture this mask, and all the silicon in the center of the substrate was removed by etching, leaving only the silicon nitride film and the metal pattern formed on it. It was confirmed that this is possible.

[0015]

[Effects of the Invention] As explained above, the first method according to the present invention
According to the invention, since the non-etched side of the etching substrate is kept in a non-contact state and at the same time the etching solution is prevented from penetrating, there is no contact between the pattern-forming surface of the etching substrate and the etching solution. Damage to the pattern can be reliably prevented and the yield of substrate manufacturing can be improved. Further, according to the second aspect of the present invention, since a preload is applied to the non-contact portion of the pattern forming surface of the etching substrate, destruction of the substrate during etching can be reliably prevented and the yield of substrate manufacturing can be improved. can be done. Furthermore, according to the third aspect of the present invention, since the same amount of preload is applied from the non-contact surface side of the etching substrate to the liquid pressure acting on the etching surface of the etching substrate, the etching portion of the etching substrate Even if the substrate pressure is reduced to about 1 μm, the etched substrate will not be damaged by the pressure, and even if the pressure balance collapses during etching, this fluctuation can be suppressed, and the yield of substrate manufacturing can be improved. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a sectional view illustrating the structure of a first embodiment of an etching substrate holding cassette according to the present invention.

FIG. 2 is a sectional view illustrating another embodiment of the sealing material for the etching substrate holding cassette according to the present invention.

FIG. 3 is a sectional view illustrating the structure of a second embodiment of the etching substrate holding cassette according to the present invention.

FIG. 4 is a sectional view illustrating the structure of a third embodiment of the etching substrate holding cassette according to the present invention.

FIG. 5 is a sectional view illustrating the configuration of a fifth embodiment of the etching substrate holding cassette according to the present invention.

[Explanation of symbols]

1 Nitride film 2 Si substrate 3 Metal pattern 4 Cassette support 5a Seal material 5b Seal material 6 Liquid reservoir body 7 Etching solution 8 Preload chamber 9 Gas introduction hole 10 Gas valve 11 Pressure gauge 12 Liquid introduction hole 13 Liquid valve 14 Cylinder 15 Gas distribution pipe 16 Liquid injection valve 17 Etching tank

Claims (3)

[Claims] 1. A concave cassette support in which an etching solution is accommodated and an etching substrate is immersed therein, and the cassette support is accommodated in the cassette support and keeps a pattern-formed surface of the etching substrate out of contact with the etching solution. 1. An etching substrate holding cassette characterized in that it is provided with a flexible sealing material that holds an outer peripheral portion thereof. 2. A concave cassette support in which an etching solution is accommodated and an etching substrate is immersed therein, and the cassette support is accommodated in the cassette support and keeps the patterned surface of the etching substrate out of contact with the etching solution. a flexible sealing material that holds the outer peripheral portion, a prepressure chamber that is formed in the cassette support facing the etching substrate and applies preload to a non-contact portion of the pattern forming surface of the etching substrate, and the prepressure chamber. An etching substrate holding cassette, comprising a pressure supply means for supplying an appropriate pressure to the etching substrate holding cassette. 3. A concave cassette support that accommodates an etching solution and immerses the etching substrate; and a cassette support that is accommodated within the cassette support and keeps the patterned surface of the etching substrate out of contact with the etching solution. a flexible sealing material that holds the outer peripheral portion, a prepressure chamber that is formed in the cassette support facing the etching substrate and applies preload to a non-contact portion of the pattern forming surface of the etching substrate, and the prepressure chamber. An etching substrate holding cassette comprising: a pressure supply means for supplying an appropriate pressure to the etching solution; and a pressure adjustment means for always adjusting the pressure of the etching solution and the prepressure of the prepressure chamber to be equal.