JPH03166748A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To accurately set an interval of grooves having depths by providing a step of ion implanting selectively in high energy and high concentration in a first region of a mask material. CONSTITUTION:Ions of high energy and high concentration are implanted in a first region A of a mask material 10 formed on the entire main surface of a semiconductor substrate 1. Then, when first and second regions A, B of the material 10 are selectively etched, the etching of the region A is advanced faster than that of the region B, and the region of the substrate 1 corresponding to the region A is slightly etched. Since the patterning of the material 10 is once in this manner, deviation of the mask does not occur, and an interval between the grooves having depths can be accurately set.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, for example, a method for manufacturing a semiconductor device having a groove-shaped isolation structure for separating each element formed on a semiconductor substrate. Regarding.

[Conventional technology]

FIGS. 2A to 2C are cross-sectional process diagrams showing a conventional method of manufacturing this type of semiconductor device.

First, referring to FIG. 2A, N-type impurities are introduced into the surface of P-type semiconductor substrate 1 by ion implantation, and heat treatment is performed to form N+-type buried layer 2 with a high impurity concentration. Thereafter, an N1 type epitaxial layer 3 with a low impurity concentration is formed on this N+ type buried layer 2.

Next, referring to FIG. 2B, the N-type epitaxial layer 3
1μ film thickness on top! An oxide film 4 having a thickness of about n is formed. This oxide film 4 is deposited thereon and selectively etched away using the patterned resist 5 as a mask.

Then, as shown in FIG. 2C, anisotropic etching is performed on the substrate (N-type epitaxial layer 3, N+-type buried layer 2, P-type semiconductor substrate 1) using the selectively etched oxide film 4 as a mask. A groove G is formed to a depth that reaches the P type semiconductor substrate 1.

[Problem to be solved by the invention]

According to the conventional semiconductor device manufacturing method, when forming grooves of different depths, one step of patterning the resist 5 and the subsequent etching process are required for each groove of each depth. The problem was that the number was increasing. Additionally, due to the accuracy of the patterning technology of the resist 5, positional deviations (mask deviations) occur between the patterns of the resist 5 formed for each groove of each depth, making it impossible to set the perfect spacing between each depth appropriately. There was a problem.

This invention was made to solve the above-mentioned problems, and provides a method for manufacturing a semiconductor device that requires a small number of steps and can accurately set the interval between grooves of each depth. With the goal.

[Means to solve the problem]

A method for manufacturing a semiconductor device according to the present invention includes the steps of preparing a semiconductor substrate, forming a mask material all over one main surface of the semiconductor substrate, and selectively forming a mask material on a first region of the mask material. a step of implanting high energy and high concentration ions, a step of selectively etching the first region and a second region of the mask, and etching the semiconductor substrate using the etched mask material as a mask. It has a process of

[Effect]

In the present invention, high-energy, high-concentration ions are implanted into a first region of a mask material formed over one main surface of a semiconductor substrate. Next, when the first region and the second region of the mask material are selectively etched, the first region of the mask material is etched faster than the second region, and the semiconductor corresponding to the first region is etched. Areas of the substrate are also slightly etched.

〔Example〕

FIGS. 1A to 1E are cross-sectional process diagrams showing an embodiment of the method for manufacturing a semiconductor device according to the present invention.

First, as shown in FIG. IA, an N+ type buried layer 2 is formed on a P type semiconductor substrate 1 by a method similar to the conventional method.
An N-type epitaxial layer 3 is formed thereon.

Next, an oxide film 4 as a mask material is formed over the entire surface of the N1 type epitaxial layer 3. As shown in Figure IB,
A resist 10 is formed on the entire surface of the oxide film 4, and a region A (first region) in which a deep groove is desired to be formed in the substrate (N1 type epitaxial layer 3, N+ type buried layer 2, and P1 type semiconductor substrate)
The resist 10 is patterned so that the area corresponding to the area becomes a window. And the patterned resist 10
100 high energy and high concentration ions using as a mask
inject. Ions 100 are implanted into the oxide film 4 through the window of the resist 10. The oxide film 4 is damaged by the implantation of the ions 100. This damaged portion can be easily removed by etching in the next step.

Next, the resist 10 is removed and a new resist 5 is formed over the entire surface of the oxide film 4. Then, as shown in FIG.
Next, the oxide film 4 is etched using the patterned resist 5 as a mask. At this time, since the etching rate is high in the part damaged by the ions 100, the area A is shown in FIG.
A part of the N-type epitaxial layer 3 is also etched.

Next, the resist 5 is removed and anisotropic etching is performed using the oxide film 4 as a mask. Then, grooves are formed in areas A and B. The anisotropic etching is stopped when the groove in region A reaches the P-type semiconductor substrate 1. In region A, the N-type epitaxial layer 3 has been slightly etched at the time of etching the oxide film 4 as described above.
The groove formed in region B is deeper than the groove formed in region B.

According to this embodiment, grooves with different depths can be formed by one-time buttering of the resist 5 and one subsequent anisotropic etching, thereby simplifying the processing steps. Furthermore, since the resist 5 only needs to be patterned once, mask misalignment does not occur, and the intervals between the grooves at each depth can be set accurately. Furthermore, in the past, when grooves of different depths were formed and the grooves were subjected to insulation treatment to achieve insulation, insulation treatment was performed each time a groove of the same depth was formed. Since grooves of different depths can be formed at the same time, insulation can be done at once after forming the structure.
The processing steps can be simplified.

〔Effect of the invention〕

As described above, according to the present invention, since the step of selectively implanting high-energy and high-concentration ions into the first region of the mask material, the first region and the second region of the mask material are When selectively etched, the first region of the mask material is etched faster than the second region, and the semiconductor substrate corresponding to the first region is also slightly etched. As a result, when a semiconductor substrate is etched using the etched mask material as a mask, the grooves formed in the first region are deeper than the grooves formed in the second region, and the patterning of the mask material at one time is Also, trenches with different depths can be formed by etching the semiconductor substrate once, and the processing steps can be simplified. Also,
Since the mask material is battened only once, there is no possibility of mask displacement and the effect is that the intervals between the grooves at each depth can be set accurately.

[Brief explanation of the drawing]

FIGS. IA to 1E are cross sections showing an embodiment of the method for manufacturing a semiconductor device according to the present invention. FIGS. 2A to 2C are cross sections for explaining a conventional method for manufacturing a semiconductor device. It is a process diagram. In the figure, 1 is a P-type semiconductor substrate, 2 is an N+-type buried layer, 3 is an N-type epitaxial layer, 4 is an oxide film, and 10
0 is an ion, A is a first region, and B is a second region. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A step of preparing a semiconductor substrate, a step of forming a mask material all over one main surface of the semiconductor substrate, and selectively implanting high-energy and high-concentration ions into a first region of the mask material. selectively etching the first region and second region of the mask material; and etching the semiconductor substrate using the etched mask material as a mask. Production method.