DE102005057407B4 - A method of treating material having at least one recess with at least one wall in the manufacture of semiconductor devices - Google Patents

Abstract

Method of treating material having at least one recess with at least one wall in the manufacture of semiconductor devices,
characterized in that
a) at least a portion (1) of the wall (6) of the recess (5) in the material (10) targeted with ions (2) implanted at an implantation angle α> 0 ° is implanted to the vertical to the material, and
b) subsequently or in a later method step, an etching step of the material (10) is carried out, wherein the etching rate of this method step by the implanted ions (2) is selectively changed.

Description

The The invention relates to a method according to the preamble of the claim 1.

For the production of semiconductor devices, for many process steps an etching step (e.g. dry etching, wet etching) used. The etching takes place here a material due to atoms or molecules of a gas and / or by Shelling of the corrosive Material surface with Ions (as in RIE Reactive Ion Etching).

The etching rate of Trockenätzprozessschritte is usually a function of the material and the selected process parameters (e.g., ionic species, pressure, power, shape and strength of the field, etc.). The profile formation is essentially about the process parameters or the mask determines.

There the ones to be etched Structures in the material become smaller and deeper (i.e. aspect ratio is getting bigger), can the etching medium not everywhere etching effectively; i.e. the etching rate is limited. Influencing the etch rate by the process parameters or the equipment reaches its limits.

From the DE 10 2004 052 141 A1 a method for producing a conductor structure is known, wherein a raised area of a semiconductor structure is as simple as possible for a subsequent construction of an electrical component, for example a field-effect transistor. To prepare the raised area for the further construction of an electrical component, nitrogen is implanted in the vertical direction in the surface of the raised area and in the edge area of the insulating layer adjoining the raised area.

The US 2004/0180531 A1 describes a method for producing a magnetic memory module. The memory module includes a first insulating layer and a second insulating layer into which a first circuit is installed. On a third insulation layer is over the circuit formed a magnetic memory element. On the third insulation layer is applied a fourth insulation layer, covering the storage element. The fourth is followed by a fifth insulation layer, in which a slot is formed, which is down to the surface of Memory element is enough. According to one embodiment is on the fourth insulating layer before applying the fifth insulating layer an etch stop layer educated. The etch stop layer can be made of silicon nitride, silicon carbide or amorphous carbon be formed. It is also before the formation of the etch stop layer possible, the surface the fourth insulating layer of a plasma nitrogen treatment, a nitrogen-ion, Fluoride ion or exposure to carbon ion implantation.

In the US 5,541,380 discloses an anisotropic etching method wherein a crystalline silicon-based material is exposed to accelerated hydrogen ions, silicon ions or rare gas ions in the vertical direction. The exposure forms an amorphous region in said material. Subsequently, the material is exposed to an atmosphere of fluorinated halogen, specifically etching the amorphous part. For example, amorphous silicon is etched twice as fast with ClF ₃ as crystalline silicon.

Of the The present invention is based on the object, a method to create at which the etching rate can be better influenced.

These The object is achieved by a Method solved with the features of claim 1.

First, at least a portion of the wall ( 6 ) of the depression ( 5 ) of a material specifically implanted with ions at an implantation angle α> 0 ° measured to the vertical to the material and then or in a later process step carried out an etching step, wherein the etching rate of this process step is selectively changed by the implanted ions. By ion implantation, properties of the material can be specifically influenced, so that the subsequent etching can be carried out more efficiently. The etching can be advantageously designed as dry etching or wet etching.

there it is advantageous if by implanting the ions in at least A depot of atoms or molecules is created in a subarea of the material so that they are as reactant or inhibitor for the following dry etching to disposal stands. The depot serves e.g. as storage for reactants or inhibitors in places that otherwise for reactive etching media are difficult to access.

Further it is advantageous if by implanting the ions in the at least a portion of the material has the crystalline structure the material is selectively changed to influence the etching rate.

An advantageous procedure for implantation is when the spatial arrangement of the implanted ions, in particular in the form of a depot in the material is specifically controlled by the implantation angle. By choosing the implantation angle, areas that are difficult to access, eg walls of a trench, can be reached for ion implantation become.

If the geometry to be implanted is complex, e.g. a depression it is advantageous if between the material and the Implantation source a rotational relative motion is generated, so that especially in vertical areas (e.g., walls) the implant is implanted.

Also It is advantageous if the implantation depth of the ions in the material and / or the shape of the implanted portion by adjustment the implantation energy is controlled in a targeted manner. A possible Value for the implantation energy is e.g. 2 keV. But it can also be higher values (e.g., 30 keV).

there it may be particularly advantageous if the expansion and / or Shape of the implanted portion in the material by timing the ion implantation, an ion current density control and / or a control of the ion energy is controlled. If a desired Implantation profile is known in the material, so can advantageously the timing of the ion implantation, the control of the ion current density and / or the control of ion energy as a function of this preselected concentration profile take place in the subarea. The diffusion behavior of an ion species in a material is known, so that over a temperature and / or Timing, e.g. It can be determined how much ions are implanted and which areas achieve a certain concentration.

There Diffusion processes are temperature-dependent, It is advantageous if the implantation of the ions by a targeted Temperature control of the material is controlled.

Also it is advantageous if the implantation by a suitable mask, in particular resist mask is controlled specifically.

at In a further advantageous embodiment, ions are at least partially implanted at the bottom of a depression, in particular a deep trench.

Also it is advantageous if the ions at least partially in one Wall of a deep trench implanted in the material.

Also it is advantageous if the implantation in the wall by a Rotation of the material and / or rotation of the ion source at several Make the depression.

With The advantage of implanted ions are nitrogen ions and oxygen ions and / or halogen ions, in particular fluorine ions or chlorine ions, used. Here is an implantation with oxygen and / or Nitrogen ions for the generation of an etch stop layer particularly suitable. Implantation with fluorine and / or chlorine ions is for a depot formation suitable.

One Advantageous use of the method according to the invention is when the Material silicon of a substrate for the production of DRAM chips or logic chips.

The Invention will be described below with reference to the figures of Drawings on several embodiments explained in more detail. It demonstrate:

1A Figure B shows an example of an implant of an etch stop layer;

2A B, C an example of a reactant implantation;

3A , B, C as a first embodiment of the method according to the invention, a Reaktanden- / inhibitor implantation;

4A , B as a second embodiment of the method according to the invention a Reaktandenimplantation with concentration profile.

The 1A . 1B . 2A . 2 B and 2C show examples of implantation according to the prior art.

In 1A is the first step in the process of implanting a material 10 with ions 2 shown. The ion implantation is performed here with nitrogen, which is the material 10 , here silicon, penetrates and depends on the kinetic energy of the ions 2 in a subarea 1 of the material. Depending on the kinetic energy of the ions 2 , determines the depth of storage. The implantation angle α is here 0 °, since the implantation is perpendicular to the material 10 he follows.

In the present example is above the material 10 no mask arranged so that the ions 2 be implanted over the entire surface. The kinetic energy of the ions 2 determines the depth (ie the range of the ions in the material) in which a layer is formed.

In subsequent process steps, which are not shown here in detail, inter alia, a further layer 11 applied to the material (see 1B ), which is then patterned with a dry etching step (here by RIE). This will be depressions 12 etched. In principle, the etching can also with a wet chemical etching step he consequences.

The etching of the wells 12 will be at the subarea 1 with the implanted ions 2 stopped because the previous implantation the material 10 has changed so here that the etching is selective with respect to this subregion 1 is.

at this embodiment is targeted an etch stop layer produced without that a special layer must be deposited on a substrate.

In 2A , B, C, a second embodiment is shown in which the targeted change of the material 10 has another effect by ion implantation.

In 2A is a material as a starting point 10 (here again silicon) with two recesses 5 shown. The wells 5 were in a previous first etching step by means of the mask layer 13 been prepared. The aspect ratio of the well is not drawn to scale here for reasons of clarity. Typically, the aspect ratio is greater than 10. The first etch step is performed until the etch rate allows meaningful advancement in the depth of the depression. To improve the etching progress, use is then made of the second embodiment.

In 2 B becomes an implantation by means of ions 2 executed at an implantation angle α = 0 °. Here, halogen ions, in particular fluorine or chlorine ions are used.

The ions 2 encamp in the mask layer 13 not one, but on the bottom 7 the depression 5 , It forms a depot 3 of atoms or molecules in this part of the material 10 out.

Instead of a continuous layer as in the first embodiment, here is a local accumulation of ions 2 at the bottom 7 the depression 5 reached.

After the enrichment has taken place, the etching is continued with a second dry etching step. The atoms or molecules in the depot 3 are thereby exposed and are available as reactants in the bottom of the recess during the etching, in 2C through the enrichment 8th in the depression 5 shown. With these additionally provided reactants, a more uniform etching is possible.

Of the First and second dry etching steps may, but must can not be done with the same procedure.

In 3A , B, C, the first embodiment of the method according to the invention will be described. Similar to the initial situation according to 2A is also here by means of a mask layer 13 a depression 5 in a material 10 generated. However, here the first etching step is carried out in the form of wet etching. This has an undercut of the mask layer 13 educated.

The undercut recess 5 should be extended so that the walls 6 the wells 5 must be treated. For this purpose, an ion implantation is performed at an implantation angle α = 30 °. With an oblique implantation but would only a wall 6 the depression 5 exposed to implantation. For uniform implantation, the substrate is rotated and / or pivoted, which is indicated by the arrows. Alternatively or additionally, the implantation source can also be set in rotation.

Thus, the implantation radiation sweeps over the walls 6 the wells 5 , The implantation angle α is chosen so that even in the reason 7 the depression a sufficient implantation takes place.

At the end of the implantation has become on the walls 6 and at the bottom 7 the depression 5 a subarea 3 in the material 10 emerged in which the implanted ions 2 the material 10 have selectively changed so that a subsequent dry etching (see 3C ) here specifically a widening of the depression 5 can make.

Basically the etching also oblique and with a rotating table for the material is executed become.

In 4A and B is shown representing the shape of the implanted portion 3 can be specifically controlled by adjusting the ion current density (implant strength I _D ).

Usually, the propagation of ions in the material is subject 10 Fick 's law, ie the forming concentration profile with constant implantation energy is in the one - dimensional and idealized case (as in 4B shown in x-direction) an error function. However, in monocrystalline materials, eg silicon, there are preferred directions for diffusion (channeling). The implantation can be improved by a litter layer, eg of oxide on the surface of the material 10 is applied.

Since this propagation is known, the implantation energy can conversely be controlled in such a way that, for example, a constant concentration profile (see block-shaped partial area in FIG 4B ) in the material 10 formed. For this, the implantation energy will be high at the beginning, but then slowly fall off. In principle, other profiles are conceivable by controlling the implantation energy.

The dopant concentration C _D (ie, the concentration of implanted ions) may be chosen to be proportional to the change in the desired etchant reactant concentration C _r to provide a desired effect in the subsequent dry etching step.

These Consideration assumes that the temperature during implantation (also while the diffusion) is constant. Since the diffusion is also temperature dependent, can a temperature control, alternatively or in addition to the time-dependent control of the kinetic Energy of implantation, are used. A higher temperature would the diffusion rather favor, a cool down rather prevent.

The correlations associated with here 4A and 4B Of course, also in the other embodiments, alone or in combination are applicable.

The Restricted invention in their execution not to the preferred embodiments given above. Rather, a number of variants are conceivable that of the inventive method also in principle different types Make use.

1

subregion a material, e.g. in a substrate

2

ions for implantation

3

depot the ions

5

deepening (Deep trench)

6

wall

7

reason the depression

8th

enrichment the ions in the well

10

material

11

Further deposited layer

12

deepening

13

mask layer

α

implantation angle

Claims (19)

Method for treating material having at least one depression with at least one wall in the production of semiconductor components, characterized in that a) at least one subregion ( 1 ) of the wall ( 6 ) of the depression ( 5 ) in the material ( 10 ) specifically with ions ( 2 ) is implanted at an implantation angle α> 0 ° measured relative to the vertical to the material, and b) subsequently or in a later method step, an etching step of the material ( 10 ), wherein the etching rate of this process step is determined by the implanted ions ( 2 ) is changed specifically. Method according to claim 1, characterized in that that the etching step as a dry etching step or wet etching is trained. Method according to claim 1 or 2, characterized in that by the implantation of the ions ( 2 ) in at least one subarea ( 1 ) of the material ( 10 ) a depot (3) of atoms or molecules is applied so that the ions (2) are available as a reactant or inhibitor for the subsequent etching step. Method according to at least one of the preceding claims, characterized in that by the implantation of the ions ( 2 ) in the at least one subregion ( 1 ) of the material ( 10 ) the crystalline structure of the material ( 10 ) is selectively changed to influence the etching rate. Method according to at least one of the preceding claims, characterized in that the spatial arrangement of the implanted ions ( 2 ) in the material ( 10 ) is controlled by the implantation angle (α) targeted Method according to at least one of the preceding claims, characterized in that between the material ( 10 ) and the implantation source a rotational relative movement is generated, so that in particular in vertical regions of the material ( 10 ) an implantation is performed. Method according to at least one of the preceding claims, characterized in that the implantation depth of the ions ( 2 ) in the material ( 10 ) and / or the shape of the implanted portion ( 1 ) is controlled by the setting of the implantation energy targeted. Method according to at least one of the preceding claims, characterized in that the extent and / or shape of the implanted partial area ( 3 ) in the material ( 10 ) is controlled by ion implantation timing, ion current density control, and / or ion energy control. A method according to claim 8, characterized in that the timing, the control of the ion current density and / or the control of the ion energy in dependence of a preselected concentration profile of the implanted ions ( 2 ) in the subsection ( 1 ) he follows. Method according to at least one of the preceding claims, characterized in that the implantation of the ions ( 2 ) by a controlled temperature control of the material ( 10 ) is controlled. Method according to at least one of the preceding Claims, characterized in that the implantation by a suitable Mask, in particular resist mask or an oxide hard mask targeted is controlled. Method according to at least one of the preceding Claims, characterized in that by the implantation with oxygen, Nitrogen and / or carbon at least one etch stop layer in the material will be produced. Method according to at least one of the preceding claims, characterized in that the ions ( 2 ) at least partially at the bottom of a depression ( 5 ), in particular a deep trench are implanted. Method according to at least one of the preceding claims, characterized in that the ions ( 2 ) at least partially in a wall ( 6 ) of a deep trench in the material ( 10 ) are implanted. Method according to one of the preceding claims, characterized in that the implantation in the wall ( 6 ) by a rotation of the material ( 10 ) and / or rotation of the ion source at several points of the depression ( 5 ) he follows. Method according to at least one of the preceding claims, characterized in that the implanted ions ( 2 ) Nitrogen ions, oxygen ions and / or halogen ions, in particular fluorine ions or chlorine ions are. Method according to at least one of the preceding Claims, characterized in that the dry etching step is in particular of Silicon with HBr, Cl2, HCl, SF6 and / or NF3 is used as an etchant. Method according to at least one of the preceding Claims, characterized in that the dry etching by means of parallel plate reactor (RIE), inductive coupling (ICP), resonant excitation (ECR, Helicon), or microwaves becomes. Method according to at least one of the preceding Claims, characterized in that the material is silicon of a substrate for the production of DRAM chips or logic chips.